Encapsidates the genome in a ratio of 1 N per 6 ribonucleotides, protecting it from nucleases. The nucleocapsid (NC) has a helical structure. The encapsidated genomic RNA is termed the NC and serves as template for transcription and replication. During replication, encapsidation by N is coupled to RNA synthesis and all replicative products are resistant to nucleases. N is released in the blood following lysis of infected cells, it interacts then probably with FCGR2B on immune cells, inducing apoptosis and blocking inflammatory immune response. Ntail binds to a protein on thymic epithelial cells, termed Nucleoprotein Receptor (NR), inducing growth arrest (By similarity). Homomultimerizes to form the nucleocapsid. Binds to viral genomic RNA. In nucleocapsid, binds the P protein and thereby positions the polymerase on the template. Interacts with human FCGR2B protein ex vivo (By similarity). Ncore is globular and carries regions required for N self-assembly and RNA-binding. Ntail is an intrinsically disordered monomeric domain (By similarity). Belongs to the paramyxoviruses nucleocapsid family.