CD150 SLAM1 (signaling lymphocyte activation molecule, family member 1), IPO-3, CDw150
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Type 1 glycoprotein
B Cell
T Cell
Dendritic Cell
Endothelial Cell
Thymocyte
40 / 40
95 / 95

Expression
CD150,  was formally CDw150.  Expression is on the resting CD45R0-positive subpopulation of T cells, a subset of B cells, and is upregulated in activated T and B cells and dendritic cells.  CD150 is expressed in tissue, immature thymocytes and endothelial cells which are stained and germinal center B cells show cytoplasmic staining and wheras follicular mantle B cells show surface staining.  Expression is also on endothelial cells after activation and on peripheral blood memory T cells. 

Structure
MOLECULAR FAMILY NAME: Belongs to the immunoglobulin gene superfamily.

CD150 is a single-chain type-1 335 aa glycoprotein.  It contains a 27 leader sequence, a 209 aa extracellular domain which contains a Ig-like V-type and a C2 Ig-like domain and  8 potential N-glycosylation sites, a 22 aa transmembrane region and a 77 aa cytoplasmic tail which contains several potential sites for tyrosine and serine/threonine phosphorylation sites and has an ITIM motif.  An ITSM (immunoreceptor tyrosine switch motif) is characteristic of this family of proteins and allows interaction with SH2 adaptor proteins. 

Structural features place CD150 in the CD2 family, which includes CD48, CD58, CD244 (2B4) and CD229 (Ly-9).  

MOLECULAR MASS
Cell Type Unreduced Reduced Comment
B lymphocytes 65-85 kDa 75-95 kDa Protein core 41 kDa, sialic acids 10 kDa
T lymphocytes 70 kDa Protein core 40 kDa
B lymphocytes 65-85 kDa 75-95 kDa
T lymphocytes 65-85 kDa 70 kDa

POST-TRANSCRIPTIONAL MODIFICATION

Alternatively splicing yields 3 different isoforms which were cloned.  The isoforms are described as a variant membrane isoform with a truncated cytoplasmic domain, a soluble isoform lacking 30 aa encompassing the entire transmembrane domain and a cytoplasmic form lacking the leader sequemce.

POST-TRANSLATIONAL MODIFICATION

CD150 has extensive N-linked glycosylation which is asparagine-linked and has terminal sialic acid residues on oligosaccharide chains.  The intracytoplasmic domain with 77 aa has tyrosine and serine/threonine phosphorylation sites.  The 3 of 4 tyrosine phosphorylation sites form a potential binding site for SH2 domains.  Variation in different in Mol Wts from different cells attributes to N-glycosylation and enzymatic removal of carbohydrate reduces the Mol Wt to 40 kDa-reduced.

Ligands
LIGANDS AND MOLECULES ASSOCIATED WITH CD150
Molecule Comment
CD150 High affinity self ligand
Tyrosine and serine/threonine kinases Associates in B cells
Tyrosine phosphatase CD45 Associates in B cells
Crosslinking of ligand(s) enhances proliferation and Ig production by activated B cells.



Function
In vitro studies suggest that CD150 may bind homophilically, leading to cellular activation.  However, the physiological; function is unknown.  Ligation of CD150 leads to inteferon γ production and this appears to be physiologically relevant because several viruses have evolved strategies for modulating CD150 mediated activation.  CD150 is a signaling lymphocyte activation molecule (SLAM).  It is involved in T cell activation and is an important molecule associated with intracellular adaptor protein SAP which blocks recruitment of the SH2 domain containing phosphatase SHP-2 to the cytoplasmic tail of CD150.  High-affinity self-ligation is considered important in T and B cell stimulation and the consequences of ligation differ in these cells.  Absence of SAP causes X-linked lymphoproliferative disease which is due to abnormalities in T and B cell interactions leading to an inability to properly control the proliferation of B cells caused by Epstein Barr Virus (EBV) infection.  CD150 also contributes to the enhancement of immuno-stimulatory functions of dendritic cells that are observed following the addition of IL-1 in vitro.  CD150 acts as a co-stimulatory molecule on B lymphocytes and dendritic cells.  Binding of CD150 to its ligand(s) enhances proliferation and Ig production by activated B cells.  This makes CD150 a receptor for a co-stimulatory signal, not a co-stimulatory molecule.  The CD150 mAb A12 enhances Ag-induced proliferation of CD4+ T cells and can directly stimulate proliferation of previously activated T cells even as an Fab fragment. This mAb increases IFNg  but not IL-4, production of Ag-activated TH0, TH1 and TH2 clones.

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF CD150 IN INTACT ANIMAL

CD150 has potential diagnostic applications because it is differentially expressed on monocytes in autoimmune disease.  CD150 is a receptor for measles virus infection.
 

Comments
MOLECULAR INTERACTIONS -
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD150: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD150
Molecule Comment
Tyrosine and serine/threonine kinases In B lymphoblastoid cell lines
Tyrosine phosphatase (possible CD45) In B lymphoblastoid cell lines

ADDITIONAL INSIGHTS

Important questions remain. What are the ligands for surface and secreted forms?  What signal transduction pathways are triggered by CD150 in T and B lymphocytes?

Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene 6504Q13291
Antibodies
A12   View Reactivity

Revised June 25, 2008


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