CD48 | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Identifiers | |||||||||||||||||||||||||||||||||||||||||||||||||||
Aliases | CD48 , BCM1, BLAST, BLAST1, MEM-102, SLAMF2, hmCD48 molecule | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 109530 MGI: 88339 HomoloGene: 1347 GeneCards: CD48 | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Wikidata | |||||||||||||||||||||||||||||||||||||||||||||||||||
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CD48 antigen (Cluster of Differentiation 48) also known as B-lymphocyte activation marker (BLAST-1) or signaling lymphocytic activation molecule 2 (SLAMF2) is a protein that in humans is encoded by the CD48 gene. [5]
CD48 is a member of the CD2 subfamily of the immunoglobulin superfamily (IgSF) which includes SLAM (signaling lymphocyte activation molecules) proteins, such as CD84, CD150, CD229 and CD244. CD48 is found on the surface of lymphocytes and other immune cells, dendritic cells and endothelial cells, and participates in activation and differentiation pathways in these cells. [5]
CD48 was the first B-cell-specific cellular differentiation antigen identified in transformed B lymphoblasts. [6] [7]
The gene for CD48 is located in chromosome 1q23 and contains 4 exons, each exon encoding one of the 4 domains of CD48: signal peptide, variable (V) domain, constant 2 (C2) domain and the glycophosphatidylinositol anchor (GPI anchor). The cDNA sequence of 1137 nucleotides encodes a 243 amino acid polypeptide of about 45 kDa. [8] [9] It consists of a 26 amino acid signal peptide, 194 amino acids of mature CD48 (V and C2 domains) and the C-terminal 23 amino acid segment comprising the GPI anchor. [10] [11] The GPI linkage of CD48 to the cell surface is through serine residue 220. [10] [11] CD48 does not have a transmembrane domain, however, but is held at the cell surface by a GPI anchor via a C-terminal domain which can be cleaved to yield a soluble form of the receptor. [5] The CD48 protein is heavily glycosylated, with five possible asparagine-linked glycosylation sites at positions 40, 44, 104, 162 and 189, respectively. [6] [7] [8] [12] [13] Approximately 35-40% of the total molecular weight is attributed to the carbohydrate side chains. [12] [13] [14]
CD48 was found to have a very low affinity for CD2 with dissociation constant () < 0.5 mM. [15] It was found that the preferred ligand of CD48 is 2B4 (CD244), which is also a member of the CD2 subfamily SLAM of IgSF expressed on natural killer cells (NK cells) and other leukocytes. The affinity of CD244 for CD48 is at = 8 μM which is about 5 - 10 times stronger than for CD2. [16] [17] [18]
CD48 is expressed on all peripheral blood lymphocytes (PBL) including T cells, B cells, NK cells and thymocytes. [7] [8] [14] [19] It is also found on the surface of activated T cells, mast cells, monocytes and granulocytes. [12] Like all other GPI anchor protein (GPI-AP), CD48 is deficient in erythrocytes (red blood cells).
CD48 and CD2 molecular coupling together with other interaction pairs of CD28 and CD80, TCR and peptide-MHC and LFA-1 and ICAM-1 contribute to the formation of an immunological synapse between a T cell and an antigen-presenting cell. [20] CD48 interaction with CD2 has been shown to promote lipid raft formation, T cell activation and the formation of caveolae for macrophages through cell signal transduction via GPI moieties. [21] [22]
CD48 is being investigated amongst other markers in research on inflammation markers and therapies for HIV/AIDS.
Heterozygous germline mutation in a patient was associated with a recurrent inflammatory syndrome resembling hemophagocytic lymphohistiocytosis. [23]
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A cytotoxic T cell (also known as TC, cytotoxic T lymphocyte, CTL, T-killer cell, cytolytic T cell, CD8+ T-cell or killer T cell) is a T lymphocyte (a type of white blood cell) that kills cancer cells, cells that are infected by intracellular pathogens (such as viruses or bacteria), or cells that are damaged in other ways.
The immunoglobulin superfamily (IgSF) is a large protein superfamily of cell surface and soluble proteins that are involved in the recognition, binding, or adhesion processes of cells. Molecules are categorized as members of this superfamily based on shared structural features with immunoglobulins ; they all possess a domain known as an immunoglobulin domain or fold. Members of the IgSF include cell surface antigen receptors, co-receptors and co-stimulatory molecules of the immune system, molecules involved in antigen presentation to lymphocytes, cell adhesion molecules, certain cytokine receptors and intracellular muscle proteins. They are commonly associated with roles in the immune system. Otherwise, the sperm-specific protein IZUMO1, a member of the immunoglobulin superfamily, has also been identified as the only sperm membrane protein essential for sperm-egg fusion.
CD11c, also known as Integrin, alpha X (ITGAX), is a gene that encodes for CD11c.
Integrin, alpha L , also known as ITGAL, is a protein that in humans is encoded by the ITGAL gene. CD11a functions in the immune system. It is involved in cellular adhesion and costimulatory signaling. It is the target of the drug efalizumab.
Thy-1 or CD90 is a 25–37 kDa heavily N-glycosylated, glycophosphatidylinositol (GPI) anchored conserved cell surface protein with a single V-like immunoglobulin domain, originally discovered as a thymocyte antigen. Thy-1 can be used as a marker for a variety of stem cells and for the axonal processes of mature neurons. Structural study of Thy-1 led to the foundation of the Immunoglobulin superfamily, of which it is the smallest member, and led to some of the initial biochemical description and characterization of a vertebrate GPI anchor and also the first demonstration of tissue specific differential glycosylation.
CD2 is a cell adhesion molecule found on the surface of T cells and natural killer (NK) cells. It has also been called T-cell surface antigen T11/Leu-5, LFA-2, LFA-3 receptor, erythrocyte receptor and rosette receptor.
Leukosialin also known as sialophorin or CD43 is a transmembrane cell surface protein that in humans is encoded by the SPN (sialophorin) gene.
CD59 glycoprotein, also known as MAC-inhibitory protein (MAC-IP), membrane inhibitor of reactive lysis (MIRL), or protectin, is a protein that in humans is encoded by the CD59 gene. It is an LU domain and belongs to the LY6/uPAR/alpha-neurotoxin protein family.
CD5 is a cluster of differentiation expressed on the surface of T cells and in a subset of murine B cells known as B-1a. The expression of this receptor in human B cells has been a controversial topic and to date there is no consensus regarding the role of this receptor as a marker of human B cells. B-1 cells have limited diversity of their B-cell receptor due to their lack of the enzyme terminal deoxynucleotidyl transferase (TdT) and are potentially self-reactive. CD5 serves to mitigate activating signals from the BCR so that the B-1 cells can only be activated by very strong stimuli and not by normal tissue proteins. CD5 was used as a T-cell marker until monoclonal antibodies against CD3 were developed.
CD58, or lymphocyte function-associated antigen 3 (LFA-3), is a cell adhesion molecule expressed on Antigen Presenting Cells (APCs), particularly macrophages, and other tissue cells.
Leukocyte surface antigen CD53 is a protein that in humans is encoded by the CD53 gene.
CD81 molecule, also known as CD81, is a protein which in humans is encoded by the CD81 gene. It is also known as 26 kDa cell surface protein, TAPA-1, and Tetraspanin-28 (Tspan-28).
CD244 also known as 2B4 or SLAMF4 is a protein that in humans is encoded by the CD244 gene.
Semaphorin-4D (SEMA4D) also known as Cluster of Differentiation 100 (CD100), is a protein of the semaphorin family that in humans is encoded by the SEMA4D gene.
CD84 is a human protein encoded by the CD84 gene.
SLAM family member 6 is a protein that in humans is encoded by the SLAMF6 gene.
CD6 is a human protein encoded by the CD6 gene.
Immunoglobulin superfamily, member 2 (IGSF2) also known as CD101, is a human gene.
CD8a, is a human gene.
Ly6 also known as lymphocyte antigen 6 or urokinase-type plasminogen activator receptor (uPAR) is family of proteins that share a common structure but differ in their tissue expression patterns and function. Ly6 are cysteine-rich proteins that form disulfide bridges and contain a LU domain. These proteins are GPI-anchored to the cell membrane or are secreted. A total of 35 human and 61 mouse Ly6 family members have been identified. Depending on which tissues they are expressed in, LY6 family members have different roles. They are expressed in various types of tissues and their expression dependent on the stage of cell differentiation. For example, they are involved in cell proliferation, cell migration, cell–cell interactions, immune cell maturation, macrophage activation, and cytokine production. Their overexpression or dysregulation, for example due to point mutations, is associated with tumorogenesis and autoimmune diseases. This family was discovered in the 1970s, and these proteins are still used as markers of distinct stage of leukocyte differentiation.
This article incorporates text from the United States National Library of Medicine, which is in the public domain.