Essential component of the RNA polymerase transcription and replication complex. Binds the viral ribonucleocapsid and positions the L polymerase on the template. May act as a chaperone for newly synthesized free N protein, so-called N(0). Plays a role in virion assembly. Homotrimer. This trimer is stabilized by binding to the L protein. Binds N(0), and N in ribonucleocapsid (By similarity). May bind to host ref(2)P (PubMed:7684462). Phosphorylated by host kinases. Phosphorylation play an important role in facilitating trimerization and possibly P-L complex formation. Belongs to the vesiculovirus protein P family.