The Gag polyprotein from retroviruses is processed by viral protease to produce the major structural proteins, including the capsid protein. The newly formed capsid protein rearranges to form the capsid core particle that surrounds the viral genome of the mature virus. The capsid is composed of two domains, the N-terminal domain (NTD), which contributes to viral core formation, and the C-terminal domain (CTD), which is required for capsid dimerisation, Gag oligomerization and viral formation. The CTD contains the major homology region (MHR), a stretch of 20 amino acids that is conserved across retroviruses and is essential for viral assembly, maturation and infectivity. This entry represents the CTD which is composed of a bundle of four helices in an up and down arrangement, where helix 3 is shorter than the others.

PMID:9346481 PMID:9931251 PMID:10669613