124596 Results for: "3+ml+k2edta"

Supplier: SARSTEDT INC

The high quality of blood samples collected with the S-Monovette® blood collection system is due to the gentle aspiration technique. It has been proven to significantly reduce hemolysis rates compared to vacuum systems. As a result, erythrocytes remain intact and blood collection does not have to be repeated as often.

Supplier: Prosci

This antibody recognizes a single chain, transmembrane, heavily glycosylated protein of 90-120kDa, which is identified as CD34. Its expression is a hallmark for identifying pluripotent hematopoietic stem or progenitor cells. Its expression is gradually lost as lineage committed progenitors differentiate. CD34 is a marker of choice for staining blasts in acute myeloid leukemia. In addition, it is expressed by soft tissue tumors, such as solitary fibrous tumor and gastrointestinal stromal tumor. CD34 expression is also found in vascular endothelium. Additionally, it appears that proliferating endothelial cells overexpress this molecule than the non-proliferating endothelial cells. Anti-CD34 labels > 85% of angiosarcoma and Kaposi’s sarcoma, but shows low specificity.

Supplier: Prosci

Recognizes a protein of 50-65kDa, identified as CD16 (Workshop IV; Code N39 ) (also known low affinity Fc receptor III for IgG (FcRIII) or Leu 11). CD16 exists as a polypepetide-anchored from (FCRIIIA or CD16A) on human natural killer (NK) cells and monocytes/ macrophages and as a glycosylphosphatidylinositol (GPI)-anchored form (FcRIIIB or CD16B) on neutrophils. CD16B is polymorphic and the two alleles are termed NA1 and NA2.3 CD16 plays a role in signal transduction, NK cell activation and antibody-dependent cellular cytotoxicity. This mAb has been showed to inhibit the binding of immune complex to NK cells, inhibit cytotoxicity of NK cells, and induce calcium fluxes in NK cells and neutrophils.

Supplier: Prosci

Recognizes a protein of 130-140kDa, identified as CD22 (also known as BL-CAM). CD22 expression is restricted to normal and neoplastic B cells and is absent from other haemopoietic cell types. In B-cell ontogeny, CD22 is first expressed in the cytoplasm of pro-B and pre-B cells, and on the surface as B cells mature to become IgD+. It is not expressed by plasma cells, CD22 is found highly expressed in follicular mantle and marginal zone B-cells, and while germinal center B-cells are relatively weak. CD22 is a member of the immunoglobulin superfamily and serves as an adhesion receptor for sialic acid-bearing ligands expressed on erythrocytes and all leukocyte classes. It also associates with tyrosine kinases and play a role in signal transduction and B-cell activation.

Supplier: Prosci

This antibody recognizes CD1b, a 44kDa type I glycoprotein associated with beta2-microglobulin. It is expressed on dendritic cells, Langerhans cells, thymocytes, and T acute lymphoblastic leukemia cells. The CD1 multigene family encodes five forms of the CD1 T-cell surface glycoprotein in human, designated CD1A, 1B, 1C, 1D and 1E. CD1, a type 1 membrane protein, has structural similarity to the MHC class I antigen and has been shown to present lipid antigens for recognition by T lymphocytes. Constitutive endocytosis of CD1b molecules and the differential sorting of MHC class II from lysosomes separate peptide- and lipid antigen-presenting molecules during dendritic cell maturation. It is also expressed in interdigitating cells.

Supplier: Rockland Immunochemical

CARMA proteins belong to the membrane-associated guan-ylate kinase-like (MAGUK) family of proteins that can function as molecular scaffolds that assist assembly of signal transduction molecules. CARMA1, CARMA2, and CARMA3 share high degrees of sequence and functional homology, but their tissue-specific distribution suggests that they serve distinct biological functions in different cell types. As with CARMA1, the CARD domain of CARMA2 has been shown to specifically interact with BCL10, a protein known to function as a positive regulator of cell apoptosis and NF-kB activation. When expressed in cells, this protein activated NF-kB and induced the phosphorylation of BCL10 Alternative splicing of CARMA2 results in isoforms that possess differential effects on NF-kB activation and endoplasmic reticulum stress-induced cell death.

Supplier: Rockland Immunochemical

Apoptosis, or programmed cell death, occurs during normal cellular differentiation and development of multicellular organisms. Apoptosis is induced by certain cytokines including TNF and Fas ligand in the TNF family through their death domain containing receptors, TNFR1 and Fas. A novel death domain containing receptor was recently identified and designated DR4 (for death receptor 4). The ligand for this novel death receptor has been identified and termed TRAIL, which is a new member in the TNF family. DR4 is also called TRAIL receptor-1 (TRAIL-R1). DR4 is expressed in most of human tissues including spleen, peripheral blood leukocytes, small intestine and thymus. Like TNFR1, Fas and DR3, DR4 mediates apoptosis and NF-kB activation in many tissues and cells.

Supplier: Rockland Immunochemical

DNAL1 was identified as a potential candidate gene for primary ciliary dyskinesia (PCD), a genetically heterologous disorder characterized by chronic infections of the upper and lower airways that often leads to permanent lung damage, randomization of left/right body symmetry, and reduced fertility. DNAL1 is reported to be expressed solely in tissues carrying motile cilia for flagella and interacts with DNAH5, a protein that when mutated has been shown to result in PCD. It has been suggested that DNAL1 serves a regulatory function for DNAH5 activity in outer dynein arms of sperm flagella, respiratory cilia, and ependymal cilia. DNAL1 has also been recently identified as an HIV dependency factor (HDF), suggesting that DNAL1 may be an important drug target in HIV treatment. At least two isoforms of DNAL1 are known to exist.

Supplier: Rockland Immunochemical

XIRP1 is a member of the Xin family of proteins, containing 16 Xin repeats. The intercalated disk protein Xin protects actin filaments from depolymerization, and is able to bundle actin filaments to interact with β-catenin, which is thought to stabilize actin-based cytoskeletons. The evolutionary emergence of the Xin paralogs may have played a key role in the development of heart chambers with complete endothelial and myocardial layers. Loss of mXinα (mouse Xin homolog) results in cardiac hypertrophy and cardiomyopathy. Phosphorylation of Ser295 is thought to play a key role in XIRP signaling. Xin Actin-Binding Repeat Containing Protein 1 pS295 Antibody is ideal for researchers interested in cell cycle research.

Supplier: Labconco

Designed to provide a leak-tight environment for work with contamination-sensitive materials

Supplier: Prosci

SCUBE3 Antibody: SCUBE3 is a member of a family of secreted glycoproteins that contain N-terminal EGF-like repeats and C-terminal cysteine-rich motifs and CUB domain and is highly expressed in primary osteoblasts and bones, and to a lesser extent in heart (1,2). Other studies have shown that overexpression of SCUBE3 in mice induced cardiac hypertrophy, suggesting that it may also play a role in the regulation of cardiac growth. SCUBE3 has been shown to be an endogenous TGF-beta receptor ligand (3,4) and is thought to promote lung cancer cell mobility and invasiveness. In lung cancer cells, the secreted SCUBE3 protein was cleaved by MMP2 and MMP9, allowing the activation of the TGF-beta receptor, the increase of Smad2/3 transcriptional activity and the upregulation of expression of proteins such as TGF-beta1, VEGF, Snail, and Slug.

Supplier: Prosci

Fibulin 5(FBLN5), with 448-amino acid protein (about 50 kDa), is a recently discovered multifunctional extracellular matrix protein that mediates endothelial cell adhesion through integrin ligation, regulates cell growth and motility in a context-specific manner, and prevents elastinopathy in vivo. Fibulin-5 is abundantly expressed in great vessels and cardiac valves during embryogenesis, and in many adult tissues including the aorta, lung, uterus and skin, all of which contain abundant elastic fibres. Decreased fibulin-5 may contribute to the pathogenesis of aortic dissection by impairing elastic fiber assembly. Fibulin-5 is also a good marker of skin ageing and that the earlier loss of fibulin-5 may involve age-dependent changes in other elastic fibre components.

Supplier: Genetex

The Toll like receptor (TLR) family in mammal comprises a family of transmembrane proteins characterized by multiple copies of leucine rich repeats in the extracellular domain and IL 1 receptor motif in the cytoplasmic domain. Like its counterparts in Drosophila, TLRs signal through adaptor molecules and could constitute an important and unrecognized component of innate immunity in humans. The TRL family is a phylogenetically conserved mediator of innate immunity that is essential for microbial recognition. TLRs characterized so far activate the MyD88/interleukin 1 receptor-associated kinase (IRAK) signaling pathway. Ten human homologs of TLRs (TLR1 10) have been described. Stimulation of the NFkB signaling pathway by TLR7 suggests that it plays a role in immune response.

Supplier: Genetex

CXCR4 (fusin, LESTR or HUMSTR) is a principal coreceptor for T-cell tropic strains of HIV-1 fusion and entry of human white blood cells. CXCR4 is also required for the infection by dual-tropic strains of HIV-1 and mediates CD4 independent infection by HIV-2. The a-chemokine SDF-1 is the ligand for CXCR4 and prevents infection by T-tropic HIV-1. CXCR4 associates with the surface CD4-gp120 complex before HIV enters target cells. CXCR4 messenger RNA levels correlated with HIV-1 permissiveness in diverse human cell types. Antibodies to CXCR4 block HIV-1 and HIV-2 fusion and infection of human target cells. The amino-terminal domain and the second extracellular loop of CXCR4 serve as HIV biding sites.CXCR4 is highly expressed in brain and heart, and in white blood cells, vascular endothelial cells, and umbilical cord endothelial cells.

Supplier: Prosci

Rift Valley Fever Virus Nucleocapsid Antibody: Rift Valley Fever (RFV) virus is an arthropod-borne virus endemic to Africa that infects humans and animals that is transmitted predominantly by mosquitoes. During human infections, symptoms can range from benign fever to severe encephalitis and fatal hepatitis with hemorrhagic fever. The Bunyaviridae family of viruses to which the RVF virus belongs are spherical enveloped viruses with a tripartite RNA genome of negative or ambisense polarity. The three segments are referred to as the L, M, and S segments. The L and M segments are negative polarity and code fore the L-dependent RNA polymerase and glycoprotein precursor respectively. The S segment is of ambisense polarity and encodes the nucleoprotein and non-structural proteins.

Supplier: Rockland Immunochemical

AP2M1 antibody detects human AP2M1. The heterotetrameric coat assembly protein complex, also known as the adaptor-related protein complex 2 (AP-2), belongs to the adaptor complexes medium subunits family. The mu 1 subunit of the AP-2 complex (AP2M1) is required for the activity of a vacuolar ATPase, which is responsible for proton pumping occurring in the acidification of endosomes and lysosomes. AP2M1 has also been shown to associate with the HIV-1 protein Nef, suggesting that Nef may use AP-2 complex to enhance the rate of endocytosis of both CD4 and class I MHC. AP2M1 may also play an important role in regulating the intracellular trafficking and function of cytotoxic T-lymphocyte associated (CTLA)-4 protein. At least two isoforms of AP2M1 are known to exist. Anti-AP2M1 antibodies are ideal for investigators involved in infectious disease and enzyme research.

Supplier: Rockland Immunochemical

The fragmentation of nuclear DNA is a hallmark of apoptotic cell death. The activities of caspase and nuclease are involved in the DNA fragmentation. Caspase-activated deoxyribonuclease (CAD), also termed DNA fragmentation factor (DFF40), is one such nuclease, and is capable of inducing DNA fragmentation and chromatin condensation after cleavage by caspase-3 of its inhibitor ICAD/DFF45. Caspase and CAD independent DNA fragmentation also exists. Recent studies demonstrated that another nuclease, endonuclease G (EndoG), is specifically activated by apoptotic stimuli and is able to induce nucleosomal fragmentation of DNA independently of caspase and DFF/CAD. EndoG is a mitochondrion-specific nuclease that translocates to the nucleus and cleaves chromatin DNA during apoptosis. The homologue of mammalian EndoG is the first mitochondrial protein identified to be involved in apoptosis in C. elegans . EndoG also cleaves DNA in vitro.

Supplier: Rockland Immunochemical

The fragmentation of nuclear DNA is a hallmark of apoptotic cell death. The activities of caspase and nuclease are involved in the DNA fragmentation. Caspase-activated deoxyribonuclease (CAD), also termed DNA fragmentation factor (DFF40), is one such nuclease, and is capable of inducing DNA fragmentation and chromatin condensation after cleavage by caspase-3 of its inhibitor ICAD/DFF45. Caspase and CAD independent DNA fragmentation also exists. Recent studies demonstrated that another nuclease, endonuclease G (EndoG), is specifically activated by apoptotic stimuli and is able to induce nucleosomal fragmentation of DNA independently of caspase and DFF/CAD. EndoG is a mitochondrion-specific nuclease that translocates to the nucleus and cleaves chromatin DNA during apoptosis. The homologue of mammalian EndoG is the first mitochondrial protein identified to be involved in apoptosis in C. elegans . EndoG also cleaves DNA in vitro.

Supplier: Genetex

Chromatin is a highly specialized structure composed of tightly compacted chromosomal DNA. Gene expression within the nucleus is controlled, in part, by a host of protein complexes which continuously pack and unpack the chromosomal DNA. One of the known mechanisms of this packing and unpacking process involves the acetylation and deacetylation of the histone proteins comprising the nucleosomal core. Acetylated histone proteins confer accessibility of the DNA template to the transcriptional machinery for expression. Histone deacetylases (HDACs) are chromatin remodeling factors that deacetylate histone proteins and thus, may act as transcriptional repressors. HDACs are classified by their sequence homology to the yeast HDACs and there are currently 2 classes. Class I proteins are related to Rpd3 and members of class II resemble Hda1p.

Supplier: Genetex

Matrix metalloproteinases (MMPs) are a family of enzymes that are responsible for the degradation of extracellular matrix components such as collagen, laminin and proteoglycans. These enzymes are involved in normal physiological processes such as embryogenesis and tissue remodeling and may play an important role in arthritis, periodontitis, and metastasis.The activation and activity of MMPs are regulated by a family of endogenous inhibitors, tissue inhibitors of metalloproteinase (TIMP). TIMP2 (also called CSC-21K) is a 21 kDa glycoprotein that is expressed by a variety of cell types. It forms a non-covalent, stoichiometric complex with both latent and active MMPs. TIMP2 shows a preference for MMP-2. TIMPs are capable of altering the metastatic potential of cancer cells and have been shown to inhibit invasion and metastasis in animal models.

Supplier: Prosci

PD-1 Antibody: Cell-mediated immune responses are initiated by T lymphocytes that are themselves stimulated by cognate peptides bound to MHC molecules on antig en-presenting cells (APC). T-cell activation is generally self-limited as activated T cells express receptors such as PD-1 (also known as PDCD-1) that mediate inhibitory signals from the APC. PD-1 can bind two different but related ligands, PDL-1 and PDL-2. Upon binding to either of these ligands, signals generated by PD-1 inhibit the activation of the immune response in the absence of "danger signals" such as LPS or other molecules associated with bacteria or other pathogens. Evidence for this is seen in PD1-null mice who exhibit hyperactivated immune systems and autoimmune diseases.

Supplier: Prosci

PD-L1 Antibody: Cell-mediated immune responses are initiated by T lymphocytes that are themselves stimulated by cognate peptides bound to MHC molecules on antigen-presenting cells (APC). T-cell activation is generally self-limited as activated T cells express receptors such as PD-1 (also known as PDCD-1) that mediate inhibitory signals from the APC. PD-1 can bind two different but related ligands, PD-L1 and PD-L2. PD-L1 is a B7-related protein that inhibits cell-mediated immune responses by reducing the secretion of IL-2 and IL-10 from memory T cells. This suggests that PD-L1 may be useful in reducing allogenic CD4+ memory T-cell responses to endothelial cells, thereby reducing the likelihood of host immune responses to allografts.

Supplier: Prosci

PD-1 Antibody: Cell-mediated immune responses are initiated by T lymphocytes that are themselves stimulated by cognate peptides bound to MHC molecules on antig en-presenting cells (APC). T-cell activation is generally self-limited as activated T cells express receptors such as PD-1 (also known as PDCD-1) that mediate inhibitory signals from the APC. PD-1 can bind two different but related ligands, PDL-1 and PDL-2. Upon binding to either of these ligands, signals generated by PD-1 inhibit the activation of the immune response in the absence of "danger signals" such as LPS or other molecules associated with bacteria or other pathogens. Evidence for this is seen in PD1-null mice who exhibit hyperactivated immune systems and autoimmune diseases.

Supplier: Prosci

PD-L1 Antibody: Cell-mediated immune responses are initiated by T lymphocytes that are themselves stimulated by cognate peptides bound to MHC molecules on antigen-presenting cells (APC). T-cell activation is generally self-limited as activated T cells express receptors such as PD-1 (also known as PDCD-1) that mediate inhibitory signals from the APC. PD-1 can bind two different but related ligands, PD-L1 and PD-L2. PD-L1 is a B7-related protein that inhibits cell-mediated immune responses by reducing the secretion of IL-2 and IL-10 from memory T cells. This suggests that PD-L1 may be useful in reducing allogenic CD4+ memory T-cell responses to endothelial cells, thereby reducing the likelihood of host immune responses to allografts.

Supplier: Prosci

PD-1 Antibody: Cell-mediated immune responses are initiated by T lymphocytes that are themselves stimulated by cognate peptides bound to MHC molecules on antig en-presenting cells (APC). T-cell activation is generally self-limited as activated T cells express receptors such as PD-1 (also known as PDCD-1) that mediate inhibitory signals from the APC. PD-1 can bind two different but related ligands, PDL-1 and PDL-2. Upon binding to either of these ligands, signals generated by PD-1 inhibit the activation of the immune response in the absence of "danger signals" such as LPS or other molecules associated with bacteria or other pathogens. Evidence for this is seen in PD1-null mice who exhibit hyperactivated immune systems and autoimmune diseases.

Supplier: VWR

The VWR® PCR thermal cycler XT⁹⁶ combines industry-inspired innovation with the reliable quality of German manufacturing – housing both in a compact, low noise ventilation design that fits on virtually any bench top. For optimising PCR's, the XT⁹⁶ is also available with a gradient function.
The VWR® PCR thermal cycler XT⁹⁶ offers a powerful, yet easy to use software interface, as well as a host of other innovative features.

Supplier: Prosci

Initiation of transcription by RNA polymerase II requires the activities of more than 70 polypeptides. The protein that coordinates these activities is the basal transcription factor TFIID, which binds to the core promoter to position the polymerase properly, serves as the scaffold for assembly of the remainder of the transcription complex, and acts as a channel for regulatory signals. TFIID is composed of the TATA-binding protein (TBP) and a group of evolutionarily conserved proteins known as TBP-associated factors or TAFs. TAFs may participate in basal transcription, serve as coactivators, function in promoter recognition or modify general transcription factors (GTFs) to facilitate complex assembly and transcription initiation. TAF1 encodes the largest subunit of TFIID. This subunit binds to core promoter sequences encompassing the transcription start site. It also binds to activators and other transcriptional regulators, and these interactions affect the rate of transcription initiation. This subunit contains two independent protein kinase domains at the N and C-terminals, but also possesses acetyltransferase activity and can act as a ubiquitin-activating/conjugating enzyme.Initiation of transcription by RNA polymerase II requires the activities of more than 70 polypeptides. The protein that coordinates these activities is the basal transcription factor TFIID, which binds to the core promoter to position the polymerase properly, serves as the scaffold for assembly of the remainder of the transcription complex, and acts as a channel for regulatory signals. TFIID is composed of the TATA-binding protein (TBP) and a group of evolutionarily conserved proteins known as TBP-associated factors or TAFs. TAFs may participate in basal transcription, serve as coactivators, function in promoter recognition or modify general transcription factors (GTFs) to facilitate complex assembly and transcription initiation. This gene encodes the largest subunit of TFIID. This subunit binds to core promoter sequences encompassing the transcription start site. It also binds to activators and other transcriptional regulators, and these interactions affect the rate of transcription initiation. This subunit contains two independent protein kinase domains at the N and C-terminals, but also possesses acetyltransferase activity and can act as a ubiquitin-activating/conjugating enzyme. Two transcripts encoding different isoforms have been identified for this gene.

Supplier: Prosci

Guanine nucleotide-binding proteins (G proteins) form a large family of signal-transducing molecules. They are found as heterotrimers made up of alpha, beta, and gamma subunits. Members of the G protein family have been characterized most extensively on the basis of the alpha subunit, which binds guanine nucleotide, is capable of hydrolyzing GTP, and interacts with specific receptor and effector molecules. The G protein family includes Gs and Gi, the stimulatory and inhibitory GTP-binding regulators of adenylate cyclase; Go, a protein abundant in brain (GNAO1); and transducin-1 (GNAT1) and transducin-2 (GNAT2), proteins involved in phototransduction in retinal rods and cones, respectively.Guanine nucleotide-binding proteins (G proteins) form a large family of signal-transducing molecules. They are found as heterotrimers made up of alpha, beta, and gamma subunits. Members of the G protein family have been characterized most extensively on the basis of the alpha subunit, which binds guanine nucleotide, is capable of hydrolyzing GTP, and interacts with specific receptor and effector molecules. The G protein family includes Gs (MIM 139320) and Gi, the stimulatory and inhibitory GTP-binding regulators of adenylate cyclase; Go, a protein abundant in brain (GNAO1; MIM 139311); and transducin-1 (GNAT1; MIM 139330) and transducin-2 (GNAT2; MIM 139340), proteins involved in phototransduction in retinal rods and cones, respectively (Sullivan et al., 1986 [PubMed 3092218]; Bray et al., 1987 [PubMed 3110783]). Suki et al. (1987) [PubMed 2440724] concluded that the human genome contains at least 3 nonallelic genes for alpha-i-type subunits of G protein; see, e.g, GNAI2 (MIM 139360), GNAI3 (MIM 139370), and GNAIH (MIM 139180).[supplied by OMIM]. Sequence Note: The RefSeq transcript and protein were derived from genomic sequence to make the sequence consistent with the reference genome assembly. The genomic coordinates used for the transcript record were based on alignments. Publication Note: This RefSeq record includes a subset of the publications that are available for this gene. Please see the Entrez Gene record to access additional publications.

Supplier: Prosci

PCBP2 appears to be multifunctional. It along with PCBP-1 and hnRNPK corresponds to the major cellular poly (rC)-binding proteins. This protein together with PCBP-1 also functions as translational coactivators of poliovirus RNA via a sequence-specific interaction with stem-loop IV of the IRES and promote poliovirus RNA replication by binding to its 5'-terminal cloverleaf structure. It has also been implicated in translational control of the 15-lipoxygenase mRNA, human Papillomavirus type 16 L2 mRNA, and hepatitis A virus RNA. The protein is also suggested to play a part in formation of a sequence-specific alpha-globin mRNP complex which is associated with alpha-globin mRNA stability. This gene and PCBP-1 has paralogues PCBP3 and PCBP4 which is thought to arose as a result of duplication events of entire genes.The protein encoded by this gene appears to be multifunctional. It along with PCBP-1 and hnRNPK corresponds to the major cellular poly (rC)-binding proteins. It contains three K-homologous (KH) domains which may be involved in RNA binding. This encoded protein together with PCBP-1 also functions as translational coactivators of poliovirus RNA via a sequence-specific interaction with stem-loop IV of the IRES and promote poliovirus RNA replication by binding to its 5'-terminal cloverleaf structure. It has also been implicated in translational control of the 15-lipoxygenase mRNA, human Papillomavirus type 16 L2 mRNA, and hepatitis A virus RNA. The encoded protein is also suggested to play a part in formation of a sequence-specific alpha-globin mRNP complex which is associated with alpha-globin mRNA stability. This multiexon structural mRNA is thought to be retrotransposed to generate PCBP-1 intronless gene which has similar functions. This gene and PCBP-1 has paralogues PCBP3 and PCBP4 which is thought to arose as a result of duplication events of entire genes. It also has two processed pseudogenes PCBP2P1 and PCBP2P2. There are presently two alternatively spliced transcript variants described for this gene.

Supplier: Prosci

SFRS1 is a member of the arginine/serine-rich splicing factor protein family, and functions in both constitutive and alternative pre-mRNA splicing. The protein binds to pre-mRNA transcripts and components of the spliceosome, and can either activate or repress splicing depending on the location of the pre-mRNA binding site. The protein's ability to activate splicing is regulated by phosphorylation and interactions with other splicing factor associated proteins. Multiple transcript variants encoding different isoforms have been found for this gene.Alternative mRNA splicing plays an important role in development and differentiation; many transcripts are spliced differently in distinct cell types and tissues. Both constitutive and alternative splicing occurs on spliceosomes, which are complex particles composed of small nuclear ribonucleoproteins (snRNPs) and non-snRNP proteins. The SR family of non-snRNP splicing factors is characterized by the presence of an RNA recognition motif and a serine- and arginine-rich (SR) domain. SR proteins are required at early stages of spliceosome assembly, have distinct but overlapping specificities for different pre-mRNAs, and can alter splice site choice, suggesting that they may be involved in the regulation of alternative splicing in vivo. Two of the SR proteins, ASF/SF2 (SFRS1) and SC35 (SFRS2; MIM 600813), have been extensively characterized.Alternative mRNA splicing plays an important role in development and differentiation; many transcripts are spliced differently in distinct cell types and tissues. Both constitutive and alternative splicing occurs on spliceosomes, which are complex particles composed of small nuclear ribonucleoproteins (snRNPs) and non-snRNP proteins. The SR family of non-snRNP splicing factors is characterized by the presence of an RNA recognition motif and a serine- and arginine-rich (SR) domain. SR proteins are required at early stages of spliceosome assembly, have distinct but overlapping specificities for different pre-mRNAs, and can alter splice site choice, suggesting that they may be involved in the regulation of alternative splicing in vivo. Two of the SR proteins, ASF/SF2 (SFRS1) and SC35 (SFRS2; MIM 600813), have been extensively characterized (Bermingham et al., 1995).[supplied by OMIM].