CD20 & CD22

This gene encodes a member of the membrane-spanning 4A gene family. Members of this nascent protein family are characterized by common structural features and similar intron/exon splice boundaries and display unique expression patterns among hematopoietic cells and nonlymphoid tissues. This gene encodes a B-lymphocyte surface molecule which plays a role in the development and differentiation of B-cells into plasma cells. This family member is localized to 11q12, among a cluster of family members. Alternative splicing of this gene results in two transcript variants which encode the same protein.

CD22 is a B-cell-specific transmembrane glycoprotein belonging to the SIGLEC (sialic acid-binding immunoglobulin-like lectin) family. It is encoded by the CD22 gene located on chromosome 19q13.1. CD22 plays a crucial role in B-cell signaling and immune response modulation. It acts primarily as an inhibitory co-receptor that regulates B-cell receptor (BCR) signaling, thereby preventing overactivation of B cells and reducing the risk of autoimmunity. CD22 binds to sialylated glycans and recruits SHP-1 (Src homology region 2 domain-containing phosphatase-1), a phosphatase that dampens signaling cascades.