CD100 SEMA4D (semaphorin-4D)
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Type 1 glycoprotein
Myeloid Cell
Hematopoietic Cell
T Cell
B Cell
Nonhematopoietic Cell
Germinal Center
Kidney
Brain
Heart
T Lymphocyte
120 / 120
150 / 150
300 / 300

Expression
CD100 is expressed on most hematopoietic cells with the exception of  immature bone marrow cells, red blood cells, platelets, erythrocytes, eosinophils, endothelial cells or K562 cells.  Expression is strong on resting T cells but weak on resting B cells and antigen presenting cells but is upregulated upon activation.  CD100 is expressed on most non-hematopoietic tissues including the embryonic and adult brain, heart and kidney.  Expression occurs on myeloid cells and is expressed on T lymphocytes and is associated with protein tyrosine phosphatase CD45 on T and B cells.  Expression is on germinal center B cells but not on mantle zone B cells. 




Structure
MOLECULAR FAMILY NAME: Belongs to the semaphorin family.

CD100 is a disulfide-linked homodimeric single-pass type-1 863 aa glycoprotein.  It contains a secretory signal sequence, an extracellular domain which contains an Ig-like C2-type domain, a 500 aa N-terminal sema domain, a 104 aa lysine-rich stalk and potential N-linked glycosylation sites, a hydrophobic transmembrane domain and a 110 aa C-terminal cytoplasmic domain which has no catalytic domains but there are consensus sites for tyrosine and serine phosphorylation.  Soluble CD100 is generated from the transmembrane via a proteolytic cascade initiated after activation of primary T and B cells.  It belongs to the subclass IV semaphorin (sema) superfamily within the Ig gene superfamily and is the only semaphorin member known to be expressed physiologically in the immune system.

MOLECULAR MASS
Cell Type Unreduced Reduced
PHA blasts 300 kDa 150 kDa
Soluble form 120 kDa

POST-TRANSCRIPTIONAL MODIFICATION: No information.

POST-TRANSLATIONAL MODIFICATION: No information.

Ligands
CD100 binds CD72 in the immune system and displays high affinity binding to plexin-B1 in non-hematpoietic tissues.

LIGANDS AND MOLECULES ASSOCIATED WITH CD100
Molecule Comment
CD45 PTPase
Serine kinase activity



Function
CD100 functions in monocyte migration, T and B cell activation and T/ B cell and T/dendritic cell interaction.  CD100 is thought to play a role in lymphocyte activation.  CD100 expresses transfectants.  Cells transfected with CD100 or soluble CD100 promotes B cell activation by inducing homotypic adhesion of B cells, downregulating expression of CD23, and modifying CD40-CD40L B cell signaling.  CD100 binds to CD72 establishing a semaphorin receptor binding pair in the immune system and may exert its positive effects on B cells by the binding  and damping CD72-negative signaling.  CD72 is constitutively tyrosine phosphorylated and associated with SHP-1 and B cells are hyporesponsive in CD100 deficient mice.  Antibody crosslinking of CD100 on T cells increases both CD2- and CD3-induced T cell proliferation. The identification of CD100 as a semaphorin suggests a possible role in neuronal guidance.  CD100 increases PMA, CD3 and CD2 induced T cell proliferation, increases CD45 induced T cell adhesion, and induces B cell homotypic adhesion.  CD100 mediates axon repulsion via its receptor plexin-B1 and may help guide developing neuronal cells.  In epithelial cells, the binding of CD100 to plexin-B1/Met (scatter factor-1) complex induces phosphorylation of the complex that is crucial for epithelial cell invasive growth.  Recombinant soluble CD100 has been shown to induce proinflammatory cytokine release by monocytes and inhibit spontaneous and MCP-3 induced migration of monocytes or a monocytic cell line.

BIOCHEMICAL ACTIVITY

CD100 is associated with PTPase and serine kinase activity.

DISEASE RELEVANCE AND FUNCTION OF CD100 IN INTACT ANIMAL

CD100 may play a functiuonal role in the immune system as as in the nervous system.

Comments
MOLECULAR INTERACTIONS -
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD100: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD100: No information.


Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanQ92854
Antibodies
A8   View Reactivity

Revised June 25, 2008


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