Essential component of the RNA polymerase transcription and replication complex. Binds the viral ribonucleocapsid and positions the polymerase on the template (By similarity). Acts as a chaperone for newly synthesized free N protein, so-called N(0). Stabilizes the L protein upon binding it (By similarity). Homotetramer. Binds to the L protein, N(0) and to the C-terminal domain of N in ribonucleocapsid (By similarity). Phosphorylated by PKC/PRKCZ, and other unknown kinases. Phosphorylation is necessary for viral transcription and replication. The N-terminus contains the majority of phosphorylated sites. Ser-249 is the major site of phosphorylation, but is not necessary for most functions (By similarity). Partially edited. RNA editing at this position consists of an insertion of one or two guanine nucleotides. The sequence displayed here is the P protein, derived from the unedited RNA. The edited RNA gives rise to the V protein (+1G) (AC P69282), and the W protein (+2G) (AC P69283). The P/V/C gene has two overlapping open reading frames. One encodes the P/V/W proteins and the other the C/Y proteins. Belongs to the respirovirus P protein family.