Plays a crucial role in virion assembly and budding. Expressed late in the virus life cycle, it acts as an inhibitor of viral transcription and RNA synthesis by interacting with the viral polymerase L. Presumably recruits the NP encapsidated genome to cellular membranes at budding sites via direct interaction with NP. Plays critical roles in the final steps of viral release by interacting with host TSG101, a member of the vacuolar protein-sorting pathway and using other cellular host proteins involved in vesicle formation pathway. The budding of the virus progeny occurs after association of protein Z with the viral glycoprotein complex SSP-GP1-GP2 at the cell periphery, step that requires myristoylation of protein Z. Also selectively represses protein production by associating with host eIF4E