SIRPB1, also known as signal-regulatory protein beta-1 isoform 1, is a type I transmembrane protein of SIRP superfamily. It is an immunoglobulin-like cell surface receptor involved in the negative regulation of receptor tyrosine kinase-coupled signaling processes. This protein also participates in the recruitment of tyrosine kinase SYK. And it acts as an activating isoform of SIRP alpha molecules that recruit SHP-1 and SHP-2 protein tyrosine phosphatases and activate counterparts, whose engagement couples to protein tyrosine kinases. Recombinant human SIRPB1 protein, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.