Siglec-2/CD22 Protein, Human (HEK293, His)

Siglec-2/CD22 Protein serves as a crucial mediator in B-cell interactions, potentially playing a role in the localization of B-cells within lymphoid tissues. Known for its ability to bind sialylated glycoproteins, including CD45, it exhibits a preference for alpha-2,6-linked sialic acid. The sialic acid recognition site may be masked by cis interactions with sialic acids on the same cell surface. During the immune response, ligand-induced tyrosine phosphorylation suggests its involvement in the regulation of B-cell antigen receptor signaling. The protein's multifaceted role encompasses positive regulation through interaction with Src family tyrosine kinases, while concurrently acting as an inhibitory receptor by recruiting cytoplasmic phosphatases via their SH2 domains to block signal transduction through dephosphorylation of signaling molecules. Siglec-2/CD22 predominately exists as a monomer of isoform CD22-beta and can also form a heterodimer with a shorter isoform. Its intricate interactions with key molecules such as PTPN6/SHP-1, LYN, SYK, PIK3R1/PIK3R2, PLCG1, GRB2, INPP5D, and SHC1, especially upon phosphorylation, highlight its pivotal role in orchestrating complex signaling networks within B-cells. Further research is essential to unravel the precise molecular pathways and functional consequences of Siglec-2/CD22 in B-cell regulation and immune responses.