| Primary Identifier | IPR000973 | Type | Family |
| Short Name | CD4 |
| description | CD4 is a glycoprotein found on the surface of T cells. It is a co-receptor that assists the T cell receptor (TCR) in communicating with an antigen-presenting cell (APC). The structure of a soluble fragment of CD4 has been determined to 2.3 A and reveals that the molecule has two intimately-associated immunoglobulin-like domains connected by a continuous beta strand. Residues implicated in HIV recognition reside in domain D1. Domain D2 is distinguished by a variation in the β-strand topologies of antibody domains that results in a truncated β-barrel with a non-standard intra-sheet disulphide bond [, ]. The binding sites for monoclonal antibodies, class II major histocompatibility complex molecules, and HIV gp120 can be mapped on the molecular surface. Ligation of CD4 by MHC-II on blood monocytes mediates macrophage differentiation and it also increases the susceptibility of blood-derived monocytes to HIV binding and subsequent infection []. |
