This family consists of various retroviral GAG (core) polyproteins and encompasses the p10 region producing the p10 protein upon proteolytic cleavage of GAG by retroviral protease. The p10 or matrix protein (MA) is associated with the virus envelope glycoproteins in most mammalian retroviruses and may be involved in virus particle assembly, transport and budding [1]. Some of the GAG polyproteins have alternate cleavage sites leading to the production of alternative and longer cleavage products (e.g. p19 Swiss:P21411) the alignment of this family only covers the approximately N-terminal (GAG) 100 amino acid region of homology to p10.

1: Complete nucleotide sequence of simian endogenous type D retrovirus with intact genome organization: evidence for ancestry to simian retrovirus and baboon endogenous virus. van der Kuyl AC, Mang R, Dekker JT, Goudsmit J; J Virol 1997;71:3666-3676. PMID:9094640