CD172a SIRPα (signal regulatory protein α), SHPS-1
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Type 1 glycoprotein
Myeloid Cell
Monocyte
Hematopoietic Progenitor Cell
Stem Cell
Dendritic Cell
Granulocyte
Brain
Nervous system
Macrophage
85 / 85
90 / 90

Expression
CD172a is expressed on CD34+ hematopoietic precursors stem/progenitor cells, neuronal tissue, macrophages, monocytes, granulocytes, dendritic cells.  It is also expressed in the central nervous system on neurons in the hippocampus, cortex, striatum, cerebellar Purkinje cells and retina.  Expression is ubiquitous, high in the brain, on myeloid cells but not on T cells.  Expression is found in low levels in heart, placenta, lung, testis, ovary, colon, liver, small intestine, prostate, spleen, kidney, skeletal muscle and pancreas.

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

CD172α is a single-pass type-1 503 aa transmembrane glycoprotein.  It contains a secretory signal sequence, an extracellular domain which contains 2 Ig-like C1-type domains and 1 Ig-like V-type domain, 4 potential N-linked glycosylation sites, several potential O-linked glycosylation sites, a putative transmembrane domain which contains a positively charged residue that interacts with the ITIM-containing DAP12/KARAP adaptor which is itself a transmembrane protein and an 100 aa long cytoplasmic domain with 2 ITIM motifs and a C-terminal proline-rich region.  The ITIMs  are phosphorylated on its tyrosine residue and associates with SHP-1 and SHP-2 phosphates which can bind when they are activated.  CD172α is a member of the Ig superfamily, a subgroup of Ig-ITIM and a member of the signal regulatory protein (SIRP).  
 

MOLECULAR MASS
Cell Type Unreduced Reduced
110 kDa

POST-TRANSCRIPTIONAL MODIFICATION

Alternative splicing yields 3 different isoforms.

POST-TRANSLATIONAL MODIFICATION: No information.



Ligands
LIGANDS AND MOLECULES ASSOCIATED WITH CD172a

CD172α binds CD47 and the lung surfactant proteins SP-A and SP-D.

Function
CD172α is an adhesion and signal transduction molecule and is known to be involved in negative regulation of receptor tyrosine kinase-coupled signaling processes.  These processes include suppression of anchorage-independent cell growth, negative regulation of immune cells, self-recognition of erythrocytes, mediation of macrophage multinucleation, skeletal muscle differentiation, entrainment of circadian clock, neuronal survival and synaptogenesis.  CD47 has been demonstrated to be the ligand for CD172a which binds to CD47 (also known as integrin associated protein-IAP) and may mediate inhibitory signals via the ITIM/SHP-2.  CD47 binding prevents maturation of immature dendritic cells and inhibits cytokine production by mature dendritic cells.  

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF CD172a
IN INTACT ANIMAL: No information.


Comments
MOLECULAR INTERACTIONS-
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD172α: No information

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD172α: No information.

Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrez140885P78324
Antibodies
74-22-15   View Reactivity
74-22-15A   View Reactivity
CC149   View Reactivity
DH59B   View Reactivity

Revised June 25, 2008


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