Cluster Of Differentiation 6 (CD6)

CD6 is a monomeric 105- or 130-kD membrane glycoprotein that is involved in T-cell activation. The size difference between the 2 CD6 forms is due to differences in phosphorylation .

By screening a human peripheral blood acute lymphocytic leukemia cell cDNA expression library with antibodies against CD6, Aruffo et al. (1991) cloned a cDNA encoding CD6. The predicted 468-amino acid protein contains a 24-amino acid signal sequence, 3 extracellular 'scavenger receptor cysteine-rich' (SRCR) domains, a membrane-spanning domain, and a 44-amino acid cytoplasmic domain. It shows significant homology to CD5 . By Northern blot analysis, CD6 is expressed as an approximately 3-kb mRNA in T cells.