What are SIRP proteins?

Signal-regulatory proteins (SIRPs) represent a new family of inhibitory/activating receptor pairs. They consist of 3 highly homologous immunoglobulin (Ig)–like domains in their extracellular regions, but differ in their cytoplasmic regions by the presence (SIRPα) or absence (SIRPβ) of immunoreceptor tyrosine-based inhibitory motifs (ITIMs).

What does SIRPγ stand for?

Crystal structure of signal regulatory protein gamma (SIRPγ) in complex with an antibody Fab fragment BMC Struct Biol. 2013 Jul 4;13:13.doi: 10.1186/1472-6807-13-13.

Which epitope is responsible for sirpα1 binding to CD47?

Using deletion constructs of SIRPα1, the epitope responsible for SIRPα1 binding to CD47 could be confined to the N-terminal Ig-like loop. Flow cytometry analysis with SIRPα/β- and SIRPβ-specific MoAbs revealed that SIRPα but not SIRPβ is expressed on CD34 + CD38 − hematopoietic cells.

Are the extracellular regions of SIRPs structurally conserved?

The three-domain extracellular regions of SIRPs are structurally conserved but show conformational flexibility in the disposition of the amino terminal ligand-binding Ig domain relative to the two membrane proximal Ig domains. Binding of a cross-reactive anti-SIRP Fab fragment to SIRPγ stabilises a …