131533 Results for: "Silver+sulphate&pageNo=10"

Supplier: Cell Systems

Our suite of specialized media provides our customers with a diverse set of tools to enhance research through consistent and stable environments for cell cultures. Cell Systems media may be used with all primary, immortalized, and established cell lines.

Supplier: Bioss

Multifunctional protein that may modulate protein degradation pathways, apoptosis, transcription, signal transduction, cell cycle progress, and genetic stability by directly or indirectly interacting with hosts factors. Does not seem to be essential for HBV infection. May be directly involved in development of cirrhosis and liver cancer (hepatocellular carcinoma). Most of cytosolic activities involve modulation of cytosolic calcium. The effect on apoptosis is controversial depending on the cell types in which the studies have been conducted. By binding to human DDB1, may affect cell viability and stimulate genome replication. May induce apoptosis by localizing in mitochondria and causing loss of mitochondrial membrane potential. May also modulate apoptosis by binding human CFLAR, a key regulator of the death-inducing signaling complex (DISC). Moderately stimulates transcription of many different viral and cellular transcription elements. Promoters and enhancers stimulated by HBx contain DNA binding sites for NF-kappa-B, AP-1, AP-2, c-EBP, ATF/CREB, or the calcium-activated factor NF-AT. May bind bZIP transcription factors like CREB1 (By similarity).

Supplier: Prosci

This mAb recognizes a protein of 130kDa, identified as Ksp-cadherin. Cadherins form a superfamily of related glycoproteins that mediate calcium-dependent cell adhesion and transmit signals from the extracellular matrix to the cytoplasm. Cadherins have been implicated in embryogenesis, tissue morphogenesis, tissue structure maintenance, cell polarization, neoplastic invasiveness and metastasis, and membrane transport. It is suggested that Ksp-cadherin is a marker for terminal differentiation of the basolateral membranes of renal tubular epithelial cells. Within the kidney, Ksp-Cadherin is found exclusively in the basolateral membrane of renal tubular epithelial cells and collecting duct cells, and not in glomeruli, renal interstitial cells, or blood vessels. Ksp-Cadherin has been suggested to distinguish Chromophobe Renal-Cell Carcinoma from Oncocytoma.

Supplier: Prosci

Eukaryotic histones are basic and water-soluble nuclear proteins that form hetero-octameric nucleosome particles by wrapping 146 base pairs of DNA in a left-handed super-helical turn sequentially to form chromosomal fiber. Two molecules of each of the four core histones (H2A, H2B, H3, and H4) form the octamer; formed of two H2A-H2B dimers and two H3-H4 dimers, forming two nearly symmetrical halves by tertiary structure. Over 80% of nucleosomes contain the linker Histone H1, derived from an intronless gene that interacts with linker DNA between nucleosomes and mediates compaction into higher order chromatin. Histones are subject to posttranslational modification by enzymes primarily on their N-terminal tails, but also in their globular domains. Such modifications include methylation, citrullination, acetylation, phosphorylation, sumoylation, ubiquitination and ADP-ribosylation.

Supplier: Prosci

The regions of relatively constant sequence beyond the variable regions of immunoglobulins are termed constant regions (C regions) and are present in both the heavy and light chains. With very few exceptions, the sites of attachment for carbohydrates on immunoglobulins are located in these C regions. These regions also function to hold the variable regions together by using the disulfide bond between them. The C regions facilitate interaction with the antigen by increasing the maximum rotation of the immunoglobulin arms. Reportedly, a large population of patients with recurrent respiratory tract infection has low IgG4 concentrations. IgG4-related sclerosing disease has been recognized as a systemic disease entity characterized by an elevated serum IgG4 level, sclerosing fibrosis, and diffuse lymphoplasmacytic infiltration with the presence of many IgG4-positive plasma cells. IgG4 is overexpressed in inflammatory pseudotumor (IPT) and under expressed in inflammatory myofibroblastic tumor (IMT). In pulmonary nodular lymphoid hyperplasia (PNLH), there are an increased number of IgG4+ plasma cells.

Supplier: Prosci

This antibody recognizes proteins of 80-200kDa, identified as different members of CEA family. CEA is synthesized during development in the fetal gut and is re-expressed in increased amounts in intestinal carcinomas and several other tumors. This mAb does not react with nonspecific cross-reacting antigen (NCA) and with human polymorphonuclear leucocytes. It shows no reaction with a variety of normal tissues and is suitable for staining of formalin/paraffin tissues. CEA is not found in benign glands, stroma, or malignant prostatic cells. Antibody to CEA is useful in detecting early foci of gastric carcinoma and in distinguishing pulmonary adenocarcinomas (60-70% are CEA+) from pleural mesotheliomas (rarely or weakly CEA+). Anti-CEA positivity is seen in adenocarcinomas from the lung, colon, stomach, esophagus, pancreas, gallbadder, urachus, salivary gland, ovary, and endocervix.

Supplier: Prosci

This antibody recognizes a glycoprotein of ~200kDa, identified as renal cell carcinoma protein, carbonic anhydrase IX / CAIX, or gp200. Its epitope resides in the carbohydrate domain of the protein. The CAIX antibody shows no significant cross-reactivity with other carbohydrate determinants, such as the Lewis blood group antigens, epithelial membrane antigen, HMFG, and AB blood group antigens. In normal kidney, CAIX is localized along the brush border of the pars convoluta and pars recta segments of the proximal tubule, as well as focally along the luminal surface of Bowman's capsule adjoining the outgoing proximal tubule. Reportedly, it is expressed by 93% of primary and 84% of metastatic renal cell carcinomas. This CAIX antibody may be useful in the investigations of carcinomas of proximal nephrogenic differentiation, especially those showing tubular differentiation.

Supplier: Prosci

This antibody recognizes a protein of 205kDa-220kDa, identified as CD45RA, an isoform of the human leukocyte common antigen (CD45). Human CD45 contains three exons which encode peptide segments designated A, B and C. The differential splicing of the exons generates at least five isoforms, ABC, AB, BC, B and O. This antibody reacts with ABC and BC isoforms. CD45RA is expressed on 40-50% of peripheral CD4+ Tcells, 50% of peripheral CD8+ T-cells, B-cells, and leukemic B-cell lines. T-cells expressing CD45RA are naive or virgin Tcells. T-cells expressing CD45RO are memory Tcells. CD45RA and CD45RO define complementary, predominantly non-overlapping populations of resting peripheral Tcells. This CD45RA antibody is useful in the study of the subpopulation of CD4+ or CD8+ T-cells. It is especially useful in differentiating T-cell lymphomas (CD45RO +ve) from B cell lymphomas (CD45RA +ve).

Supplier: Prosci

It recognizes an oncofetal glycoprotein with a single chain of 70kDa, which is identified as alpha fetoprotein (AFP). This mAb is highly specific to AFP and shows no cross-reaction with other oncofetal antigens or serum albumin. The yolk sac and the liver produce AFP during fetal life. AFP expression in adults is often associated with hepatoma or teratoma. However, hereditary persistence of alpha-fetoprotein may also be found in individuals with no obvious pathology. The protein is thought to be the fetal counterpart of serum albumin, and the AFP and albumin genes are present in tandem in the same transcriptional orientation on chromosome 4. AFP is found in monomeric as well as dimeric and trimeric forms, and binds copper, nickel, fatty acids and bilirubin. The level of AFP in amniotic fluid is used to measure renal loss of protein to screen for spinal bifida and anencephaly.

Supplier: Prosci

This mAb recognizes a 60kDa antigen associated with the mitochondria in human cells. It is a part of a new panel of reagents, which recognizes subcellular organelles or compartments of human cells. These markers may be useful in identification of these organelles in cells, tissues, and biochemical preparations. It recognizes an antigen associated with the mitochondria in human cells only. It can be used to stain the mitochondria in cell or tissue preparations and can be used as a mitochondrial marker in subcellular fractions. It produces a spaghetti-like pattern in normal and malignant cells and may be used to stain mitochondria of cells in fixed or frozen tissue sections. It can also be used with paraformaldehyde fixed frozen tissue or cell preparations. This mAb is an excellent marker for human cells in xenographic model research. It reacts specifically with human cells, including neurons and embryonic stem cells.

Supplier: Adipogen

IL-36alpha (IL-1F6), IL-36beta (IL-1F8) and IL-36gamma (IL-1F9) bind to IL-36R (IL-1Rrp2) and IL-1RAcP, activating similar intracellular signals as IL-1 and are inhibited by IL-36Ra. The expression of IL-36 cytokines has been shown to occur at different sites including the lung and skin and can be derived from diverse cell types including keratinocytes, bronchial epithelium as well as macrophages, monocytes and different T cell subsets. IL-36 family members induce the production of proinflammatory cytokines, including IL-12, IL-1beta, IL-6, TNF-alpha and IL-23 in BMDC and CD4 T cells, thus promoting neutrophil influx, dendritic cell (DC) activation, polarization of T helper type 1 (Th1) and IL-17-producing T cells (alphabeta T cells and gammadelta T cells) and keratinocyte proliferation. These cytokines may represent potential targets for immune-mediated inflammatory conditions or, alternatively, could be used as adjuvants in vaccination. IL-36gamma is also induced in the lung in various models of asthma and can be produced by bronchial epithelial cells in response to viral infection, smoke or inflammatory cytokines.

Supplier: Prosci

This gene is a member of the protocadherin alpha gene cluster, one of three related gene clusters tandemly linked on chromosome five that demonstrate an unusual genomic organization similar to that of B-cell and T-cell receptor gene clusters. The alpha gene cluster is composed of 15 cadherin superfamily genes related to the mouse CNR genes and consists of 13 highly similar and 2 more distantly related coding sequences. The tandem array of 15 N-terminal exons, or variable exons, are followed by downstream C-terminal exons, or constant exons, which are shared by all genes in the cluster. The large, uninterrupted N-terminal exons each encode six cadherin ectodomains while the C-terminal exons encode the cytoplasmic domain. These neural cadherin-like cell adhesion proteins are integral plasma membrane proteins that most likely play a critical role in the establishment and function of specific cell-cell connections in the brain. Alternative splicing has been observed and additional variants have been suggested but their full-length nature has yet to be determined.

Supplier: Prosci

Thyroglobulin is a 660kDa dimeric pre-protein with mutiple glycosylation sites. It is produced by and processed within the thyroid gland to produce the hormone thyroxine and triiodothyronine. Prior to forming dimers, thyroglobulin monomers undergo conformational maturation in the endoplasmic reticulation. The vast majority of follicular carcinomas of the thyroid will give positive immunoreactivity for anti-thyroglobulin even though sometimes only focally. Poorly differentiated carcinomas of the thyroid are frequently anti-thyroglobulin negative. Adenocarcinomas of other-than-thyroid origin do not react with this antibody. This antibody is useful in identification of thyroid carcinoma of the papillary and follicular types. Presence of thyroglobulin in metastatic lesions establishes the thyroid origin of tumor. Anti-thyroglobulin, combined with anti-calcitonin, can identify medullary carcinomas of the thyroid. Furthermore, anti-thyroglobulin, combined with anti-TTF1, can be a reliable marker to differentiate between primary thyroid and lung neoplasms.

Supplier: Prosci

The transcription factor Forkhead-box A1, also known as hepatocyte nuclear factor 3-alpha, is a member of the FOX class of transcription factors. HNF-1 (alpha and beta), HNF-3 (alpha, beta and gamma), HNF-4 (alpha and gamma), and HNF-6 compose, in part, a homeoprotein family designated the hepatocyte nuclear factor family. The various HNF-1 isoforms regulate transcription of genes in the liver as well as in other tissues such as kidney, small intestine and thymus. FOXA1 is expressed in normal breast ductal epithelium and other epithelium in different organs, such as lung, pancreas, bladder, prostate, and colon. Recently, FOXA1 has been shown to be a major determinant of estrogen-ER activity and endocrine response in breast cancer cells. Its expression correlates with estrogen receptor (ER)-positivity, especially in luminal subtype A breast cancers, which is associated with favorable prognosis. FOXA1 is useful in the sub-classification of breast carcinomas.

Supplier: Bioss

Multifunctional protein that may modulate protein degradation pathways, apoptosis, transcription, signal transduction, cell cycle progress, and genetic stability by directly or indirectly interacting with hosts factors. Does not seem to be essential for HBV infection. May be directly involved in development of cirrhosis and liver cancer (hepatocellular carcinoma). Most of cytosolic activities involve modulation of cytosolic calcium. The effect on apoptosis is controversial depending on the cell types in which the studies have been conducted. By binding to human DDB1, may affect cell viability and stimulate genome replication. May induce apoptosis by localizing in mitochondria and causing loss of mitochondrial membrane potential. May also modulate apoptosis by binding human CFLAR, a key regulator of the death-inducing signaling complex (DISC). Moderately stimulates transcription of many different viral and cellular transcription elements. Promoters and enhancers stimulated by HBx contain DNA binding sites for NF-kappa-B, AP-1, AP-2, c-EBP, ATF/CREB, or the calcium-activated factor NF-AT. May bind bZIP transcription factors like CREB1 (By similarity).

Supplier: Prosci

Gamma-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the central nervous system. There are two major classes of GABA receptors: the GABAA and the GABAB subtype of receptors. GABAA-Rs are important therapeutic targets for a range of sedative, anxiolytic, and hypnotic agents and are implicated in several diseases including epilepsy, anxiety, depression, and sub-stance abuse. The GABAA-R is a multimeric subunit complex. To date six alphas, four betas and four gamma;s, plus alternative splicing variants of some of these subunits, have been identified (Olsen and Tobin, 1990; Whiting et al., 1999; Ogris et al., 2004). Injection in oocytes or mammalian cell lines of cRNA coding for alpha- and beta-subunits results in the expression of functional GABAA-Rs sensitive to GABA. However, coexpression of a gamma-subunit is required for benzodiazepine modulation. It has recently been suggested that PKCepsilon regulates the sensitivity of GABAA alpha1beta2gamma2 receptors to ethanol and benzodiazepines through phosphorylation of serine 327 in the large intracellular loop of gamma2 (Qi et al., 2007)

Supplier: Biosensis

BDNF belongs to the neurotrophin family and regulates the survival and differentiation of neurons during development. The alterations in BDNF expression induced by various kinds of brain insult including stress, ischemia, seizure activity and hypoglycemia, may contribute to some pathologies such as depression, epilepsy, Alzheimer's, and Parkinson's disease. Microglia release BDNF that may contribute to neuroinflammation and neuropathic pain.FUNCTION: Promotes the survival of neuronal populations that are all located either in the central nervous system or directly connected to it. Major regulator of synaptic transmission and plasticity at adult synapses in many regions of the CNS. The versatility of BDNF is emphasized by its contribution to a range of adaptive neuronal responses including long-term potentiation (LTP), long-term depression (LTD), certain forms of short-term synaptic plasticity, as well as homeostatic regulation of intrinsic neuronal excitability. SUBUNIT: Monomers and homodimers. Binds to NTRK2/TRKB. SUBCELLULAR LOCATION: Secreted protein. POst translation modification: Converted into mature BDNF by plasmin (PLG). SIMILARITY: Belongs to the NGF-beta family.

Supplier: Prosci

This gene is a member of the MAGEA gene family. The members of this family encode proteins with 50 to 80% sequence identity to each other. The promoters and first exons of the MAGEA genes show considerable variability, suggesting that the existence of this gene family enables the same function to be expressed under different transcriptional controls. The MAGEA genes are clustered at chromosomal location Xq28. They have been implicated in some hereditary disorders, such as dyskeratosis congenita. This gene is a member of the MAGEA gene family. The members of this family encode proteins with 50 to 80% sequence identity to each other. The promoters and first exons of the MAGEA genes show considerable variability, suggesting that the existence of this gene family enables the same function to be expressed under different transcriptional controls. The MAGEA genes are clustered at chromosomal location Xq28. They have been implicated in some hereditary disorders, such as dyskeratosis congenita. Two transcript variants encoding the same protein have been found for this gene.

Supplier: Siemens Healthineers

DCA Vantage® Analyzer for Diabetes Control from Siemens Healthcare Diagnostics is a point-of-care system that helps you monitor glycemic control and detect early kidney disease.

Supplier: Prosci

The COL-1 antibody recognizes proteins of 80-200kDa, identified as different members of the Carcinoembryonic Antigen family. CEA is synthesized during development in the fetal gut and is re-expressed in increased amounts in intestinal carcinomas and several other tumors. This antibody does not react with nonspecific cross-reacting antigen (NCA) and with human polymorphonuclear leucocytes. It shows no reaction with a variety of normal tissues and is suitable for staining of formalin/paraffin tissues. CEA is not found in benign glands, stroma, or malignant prostatic cells. CEA antibody is useful in detecting early foci of gastric carcinoma and in distinguishing pulmonary adenocarcinomas (60-70% are positive) from pleural mesotheliomas (rarely or weakly positive). CEA antibody positivity is seen in adenocarcinomas from the lung, colon, stomach, esophagus, pancreas, gallbadder, urachus, salivary gland, ovary, and endocervix.

Supplier: Prosci

Cytokeratin 14 (CK14) belongs to the type I (or A or acidic) subfamily of low molecular weight keratins and exists in combination with keratin 5 (type II or B or basic). CK14 is found in basal cells of squamous epithelia, some glandular epithelia, myoepithelium, and mesothelial cells. Anti-CK14 is useful in differentiating squamous cell carcinomas from poorly differentiated epithelial tumors. Anti-CK14 is one of the specific basal markers for distinguishing between basal and non-basal subtypes of breast carcinomas. Anti-CK14 is also a good marker for differentiation of intraductal from invasive salivary duct carcinoma by the positive staining of basal cells surrounding the in-situ neoplasm as well as for differentiation of benign prostate from prostate carcinoma. Furthermore, this antibody has been useful in separating oncocytic tumors of the kidney from its renal mimics, and in identifying metaplastic carcinomas of the breast.

Supplier: GRANT USA INC.

General Purpose Water Baths with stable temperature control, simple interface and fast heat-up. Choose from four models each with base tray and lid included as standard.
The JB Nova general purpose unstirred water bath range benefits from key features such as the newly incorporated Set and Forget™ technology with advanced dry start and run dry protection. These are in addition to the standard features including an element free tank, user calibration, front panel lock and drain tap on sizes 12L and above

Supplier: Thermo Fisher Scientific

Accurately monitor pH, ion concentration, mV, ORP and temperature on two channels with the ORION™ Dual Star™ Benchtop Meter for advanced laboratory analysis.

Supplier: INTACT GENOMICS, INC MS

i7™ Hhot start high-fidelity DNA polymerase 2X master mix is ready to use premix which contains hot start high-fidelity DNA polymerase, dNTPs,MgCl₂, PCR enhancers and stabilizers with optimized proprietary reaction buffer. i7™ hot start high-fidelity DNA polymerase 2X master mix has the high-fidelity, sensitivity and processivity with an error rate ~2.8×102 fold lower than Taq DNA polymerase, and significantly lower than the error rates of other proofreading enzymes.

Supplier: Eppendorf

Shake more. Shake faster. The temperature-controlled (refrigerated or non-refrigerated) Eppendorf Innova S44i shaker can fit up to twice as many flasks as other shakers and is ready to reliably support high-yield expression protocols at high speeds. The Eppendorf X-Drive maintains smooth shaking for more reproducible results.

Supplier: Peprotech

The FGF family plays a central role during prenatal development and postnatal growth, and the regeneration of a variety of tissues, by promoting cellular proliferation and differentiation. The FGF ligands bind to a family of type I transmembrane tyrosine kinase receptors, which leads to dimerization and activation by sequential autophosphorylation of specific tyrosine residues. Four genes encoding structurally related FGF receptors (FGFR-1 to -4) are known. Alternative splicing of the mRNAs generates numerous forms of FGFR-1 to -3. Alternate forms of FGF receptors can exhibit different specificities with respect to ligand binding. For example, the form designated as FGFR1a (IIc) interacts predominantly with FGF-acidic (FGF1) and FGF-basic (FGF2). A frequent splicing event involving FGFR-1 and -2 results in receptors containing all three Ig domains, referred to as the alpha isoform, or only IgII and IgIII, referred to as the beta isoform. Only the alpha isoform has been identified for FGFR-3 and FGFR-4. Additional splicing events for FGFR-1 to -3, involving the C-terminal half of the IgIII domain encoded by two mutually exclusive alternative exons, generate FGF receptors with alternative IgIII domains (IIIb and IIIc). Recombinant Human FGFR1a (IIIc) Fc is a 65.2 kDa protein containing 586 amino acids. Under reducing conditions, FGFR1a migrates between 100-110 kDa on SDS-PAGE gel.

Supplier: Prosci

Zinc-alpha-2-glycoprotein (ZAG), first identified in the 1960s, derives its name from its precipitation from human plasma upon the addition of zinc salts. ZAG has since been found in secretory epithelial cells and in a range of body fluids. ZAG is identical to a lipid mobilizing factor isolated from the urine of patients with cancer cachexia and stimulates lipolysis in in vitro and in vivo experiments. Due to its expression in, and secretion from adipocytes, ZAG is considered an adipokine. Recently the clinical significance of ZAG has been clarified. ZAG expression in adipocytes is inversely related to fat mass, thus it is intimately involved in the maintenance of body weight in mice and humans. Epidemiological studies have uncovered an association between ZAG and plasma cholesterol. The non-synonymous single nucleotide polymorphism rs4215 in ZAG is associated with plasma cholesterol and obesity. Structurally ZAG possesses a class I major histocompatibility complex (MHC) protein fold. It is distinct from other members of this protein family in that it is soluble, rather than being anchored to plasma membranes, and it associates with prolactin inducible protein rather than beta2-microglobulin. Similar to peptide antigen-presenting class I MHC molecules, ZAG possesses an open apical groove between its alpha1 and alpha2 domain helices.

Supplier: Prosci

STAT1 is a member of the STAT protein family. In response to cytokines and growth factors, STAT family members are phosphorylated by the receptor associated kinases, and then form homo- or heterodimers that translocate to the cell nucleus where they act as transcription activators. This protein can be activated by various ligands including interferon-alpha, interferon-gamma, EGF, PDGF and IL6. This protein mediates the expression of a variety of genes, which is thought to be important for cell viability in response to different cell stimuli and pathogens.The protein encoded by this gene is a member of the STAT protein family. In response to cytokines and growth factors, STAT family members are phosphorylated by the receptor associated kinases, and then form homo- or heterodimers that translocate to the cell nucleus where they act as transcription activators. This protein can be activated by various ligands including interferon-alpha, interferon-gamma, EGF, PDGF and IL6. This protein mediates the expression of a variety of genes, which is thought to be important for cell viability in response to different cell stimuli and pathogens. Two alternatively spliced transcript variants encoding distinct isoforms have been described.

Supplier: Proteintech

NF-kappa-B is a pleiotropic transcription factor which is present in almost all cell types and is involved in many biological processed such as inflammation, immunity, differentiation, cell growth, tumorigenesis and apoptosis. NF-kappa-B is a homo- or heterodimeric complex formed by the Rel-like domain-containing proteins RELA/p65, RELB, NFKB1/p105, NFKB1/p50, REL and NFKB2/p52. NFKB2 appears to have dual functions such as cytoplasmic retention of attached NF-kappa-B proteins by p100 and generation of p52 by a cotranslational processing. The proteasome-mediated process ensures the production of both p52 and p100 and preserves their independent function. P52 binds to the kappa-B consensus sequence 5'-GGRNNYYCC-3', located in the enhancer region of genes involved in immune response and acute phase reactions. P52 and p100 are respectively the minor and major form; the processing of p100 being relatively poor. Isoform p49 is a subunit of the NF-kappa-B protein complex, which stimulates the HIV enhancer in synergy with p65. This antibody is a rabbit polyclonal antibody raised against residues near the C terminus of human NFKB2.

Supplier: Enzo Life Sciences

The proteasome is widely recognised as the central enzyme of non-lysosomal protein degradation. It is responsible for intracellular protein turnover and it is also critically involved in many regulatory processes and, in higher eukaryotes, in antigen processing. The 26S proteasome is the key enzyme of the ubiquitin/ATP-dependent pathway of protein degradation. The catalytic core of this unusually large (2000kDa, 450Å in length) complex is formed by the 20S proteasome, a barrel shaped structure shown by electron microscopy to comprise of four rings each containing seven subunits.  Based on sequence similarity, all fourteen 20S proteasomal subunit sequences may be classified into two groups, α and β, each group having distinct structural and functional roles. The α-subunits comprise the outer rings and the β-subunits the inner rings of the 20S proteasome. Observations of the eukaryotic proteasome and analysis of subunit sequences indicate that each ring contains seven different subunits (α7β7β7α7) with a member of each sub-family represented in each particle. Each subunit is located in a unique position within the α- or β-rings. Lmp2, Lmp7 and MECL are interferon gamma-inducible catalytic subunits of the 20S proteasome which may replace the constitutive catalytic subunits, delta, X and Z respectively, during proteasome biogenesis. Lmp2 and Lmp7 alter the cleavage site specificity of the 20S proteasome and are required for the efficient generation of T cell epitopes from a number of viral proteins and for optimal MHC class I cell surface expression.