Signal regulatory protein gamma (SIRP gamma, designated CD172g), also called SIRP beta 2, is a monomeric 45-47 kDa type I transmembrane protein belonging to the SIRP/SHPS (CD172) family of the Ig superfamily.SIRP gamma is probable immunoglobulin-like cell surface receptor. On binding with CD47, mediates cell-cell adhesion. Engagement on T-cells by CD47 on antigen-presenting cells results in enhanced antigen-specific T-cell proliferation and costimulates T-cell activation.