Essential component of the RNA polymerase transcription and replication complex. Acts as a scaffold which brings L in close proximity to the N-RNA complex. Plays a role in the segregation of the viral genome in host daughter cells during mitosis by interacting with host HMGB1, a host chromatin-remodeling DNA architectural protein, thereby stabilizing RNP on chromosomes. Interacts with host TBK1 and thus interferes with activation of cellular antiviral state. Inhibits cellular histone acetyltransferase activities. Homomultimer; only active in its oligomeric state (PubMed:15509569). Interacts with nucleoprotein/N (PubMed:9880009). Interacts with matrix/M protein (PubMed:17079312). Interacts with host TBK1 (By similarity). Interacts with polymerase L (PubMed:10756058). Interacts with host HMGB1; this interaction is required to stabilize RNP on chromosomes (PubMed:22607802). P subcellular localization is modulated by the interaction with protein X. Phosphorylated by host PKC epsilon and casein kinase II. The P/X gene has two overlapping open reading frames. One encodes the P protein and the other the X protein. The P (p24), X and P'(p16) proteins are produced by ribosomal leaky scanning.