Virus coat proteins (VCP) or capsid proteins coat the virus[1]. The various VCPs are designated as Vp1, Vp2, etc. The VCP P domain (protruding domain) in noroviruses binds histo blood group antigen receptors. The outer capsid protein VP4 is a virus spike-forming protein which mediates the virial attachment to the host epithelial cell receptors. The distal portion of Vp4 - Vp8* - is implicated in binding the cellular receptor[2]. VP4 is an outer capsid protein of non-enveloped viruses. VP4 attaches to sialic acid or to integrin heterodimers[3]. VP4 domains include: VP5* which forms the foot of the spike and acts in the permeabilization of the cell membrane and VP8* which forms the head of the spike and binds to sialic acid.
The biological assembly of HIV-I coat protein is (PDB entry 3gv2).
3D structures of virus coat proteins
Virus coat proteins 3D structures