MARV and EBOV VP30 proteins show many structural similarities. Both MARV and EBOV VP30 proteins are tightly associated with the nucleocapsid via their binding to NP ( Figure 5 ) [115, 148] . Both are highly phosphorylated at N-terminally located serine and threonine residues, and phosphorylation is crucial for their interaction with NP [148, 149] . Both contain an unusual C3H1 Zn binding domain, which is essential for the function of EBOV VP30 as transcription initiation factor, but whose functional relevance for MARV VP30 is not known [150] . It has also been shown that EBOV VP30 forms hexamers [151, 152] , binds single-stranded RNA [153] , and interacts with L [154] . However, to date, similar data for MARV VP30 are not available.