Envelope protein associated with the inner side of the enveloped virion (EV) membrane. Component of the inner side of the enveloped virion (EV) membrane. F13 is associated post-translationally with membranes. 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. F13 contains one L domain: a YPPL motif, which might interact with PDCD6IP/AIP1 (By similarity). Palmitoylated.