Cluster Of differentiation 299 (CD299)

C-type lectin domain family 4 member M is a type II integral membrane protein that is 77% identical to CD209 antigen, an HIV gp120-binding protein. This protein, like CD209, efficiently binds both intercellular adhesion molecule 3 (ICAM3) and HIV-1 gp120, and enhances HIV-1 infection of T cells. This gene is mapped to 19p13.3, in a cluster with the CD209 and CD23/FCER2 genes.

The CD209L protein has an N-terminal cytoplasmic tail with a dileucine motif, which is an internalization sequence; a 22-residue transmembrane domain; an N-linked glycosylation site; a neck containing 7 repeats of a 23-residue sequence; and carbohydrate recognition domains (CRDs), which are required for calcium-dependent mannose binding.