CD172b SIRPβ1(signal regulatory protein β1)
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Type 1 glycoprotein
Dendritic Cell
Monocyte
Granulocyte
Neural Cell
Myeloid Cell
Kidney
Testis
Brain
110 / 110
120 / 120

Expression
CD172β is expressed on monocytes, granulocytes, dendritic cells, myeloid and neural cells.  Expression is also on the brain, kidney and testis.

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

CD172β is a single-pass type-1 398 aa transmembrane glycoprotein.  It contains an extracellular domain which is 90% identical to CD172α (excluding the signal sequence), contains 2 Ig-like C-type domains and 1 Ig-like V-type domain, a transmembrane domain which contains a positively charged lysine residue that is critical to its interaction with DAP-12 and a short cytoplasmic domain which consists of only a few intracellular residues and is functionally insignificant and lacks the sequence motifs capable of recruiting SHP-1 and SHP-2 which is present in CD172α.  The protein encoded by CD172β is a member of the signal-regulatory-protein (SIRP) family.  The family have been shown to recruit SH2 domain containing protein phosphatase 1 (SHP-1) and SHP-2 and to regulate receptor tyrosine kinase-coupled signaling but not in CD172β.  One SIRP of unknown function, designated CD172β, associates with the signal transduction molecule DAP12, (CD172β/DAP12) complex formation which is required for efficient cell-surface expression.

MOLECULAR MASS

POST-TRANSCRIPTIONAL MODIFICATION

Alternative splicing yields 2 different isoforms.

POST-TRANSLATIONAL MODIFICATION

CD172β is N-glycosylated.

Ligands
LIGANDS AND MOLECULE ASSOCIATED WITH CD172β

CD172β associates with DAP12 to mediate cellular activation.


Function
CD172 (SIRP) family members are receptor type transmembrane glycoprotien known to be involved is a Ig-like cell surface receptor involved in the negative regulation of receptor tyrosine has functional-kinase-coupled signaling processes.  CD172β has activating functions in macrophages via constitutive association with DAP-12 (KARAP) homodimers.  Phosphorylation of DAP-12 intracellular immunoreceptor tyrosine-based activating (ITAM) enables association with the tyrosine kinase Syk.  This complex activates MAPK-MEK pathways and contributes to cellular activation in myeloid cells.  This protein was found to interact with TYROBP/DAP12, a protein bearing ITIM motifs and is also reported to participate in the recruitment of tyrosine kinase SYK.  Stimulation of CD172β/DAP12 induces tyrosine phosphorylation, mitogen-activated protein kinase activation and cellular activation.  In a recent study, mAb ligation of CD172β was found to enhance transmigration of polymorphonuclear cells.  However in this study, no association with DAP-12 was found but a smaller protein of 10 kDa coprecipitated with CD172β. 

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF CD172β IN INTACT ANIMAL: No information.

Comments
MOLECULAR INTERACTIONS-
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD172β: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD172β: No information.

ADDITIONAL INSIGHTS

For further information see Dietrich, J. et al (2000) J. Immunol. 164: 9-12.





Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene10326O00241
Antibodies

Revised June 25, 2008


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