The M protein has a crucial role in virus assembly and interacts with the RNP complex as well as with the viral membrane. 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. The matrix protein contains one L domain: a FPIV motif (By similarity). Belongs to the morbillivirus/respirovirus/rubulavirus M protein family.