CD4

Function

CD4 (or Cluster of Differentiation 4) is a glycoprotein found on the surface of immune cells. CD4 has 4 immunoglobulin (Ig) domains (D1-D4), a transmembrane domain and a cytoplasmic tail domain. D1 and D3 resemble Ig variable domain and D2 and D4 resemble the Ig constant domain. The D1 domain interacts with class II MHC molecules. CD4 helps T-cell receptors (TCR) interact with antigen-presenting cells. The CD4 tail interacts with tyrosine kinase Lck which activates molecular components of the signaling pathway.

Relevance

HIV-1 binds to CD4 initiating conformation changes in its protein gp120 and allowing the entry of HIV-1 to the host T-cell.^[1]

• (2nxy).^[2]

3D structures of CD4

Updated on 29-November-2015

References

1. ↑ Brady RL, Dodson EJ, Dodson GG, Lange G, Davis SJ, Williams AF, Barclay AN. Crystal structure of domains 3 and 4 of rat CD4: relation to the NH2-terminal domains. Science. 1993 May 14;260(5110):979-83. PMID:8493535
2. ↑ Zhou T, Xu L, Dey B, Hessell AJ, Van Ryk D, Xiang SH, Yang X, Zhang MY, Zwick MB, Arthos J, Burton DR, Dimitrov DS, Sodroski J, Wyatt R, Nabel GJ, Kwong PD. Structural definition of a conserved neutralization epitope on HIV-1 gp120. Nature. 2007 Feb 15;445(7129):732-7. PMID:17301785 doi:http://dx.doi.org/10.1038/nature05580