Matrix protein p15 forms the outer shell of the core of the virus, lining the inner surface of the viral membrane. Capsid protein p26 forms the conical core of the virus that encapsulates the genomic RNA-nucleocapsid complex. Nucleocapsid protein p11 encapsulates and protects viral dimeric unspliced (genomic) RNA. Binds these RNAs through its zinc fingers (By similarity). p9 plays a role in budding of the assembled particle by interacting with PDCD6IP/AIP1. Interacts with human PDCD6IP/AIP1. Late-budding domains (L domains) are short sequence motifs essential for viral particle budding. They recruit proteins of the host ESCRT machinery (Endosomal Sorting Complex Required for Transport) or ESCRT-associated proteins. p9 contains one L domain: a LYPX(n)L motif, which interacts with PDCD6IP/AIP1 (By similarity). Belongs to the equine lentivirus group gag polyprotein family. The original EMBL accession numbers (M11337 and M14855) assigned to this isolate (isolate Wyoming) have been made secondary to M16575 which is from a different isolate (clone 1365).