Protein

Location, size and function

L

A component of the viral nucleocapsid (~ 220-240 10³). Functions include transcription and replication. RNA-dependent RNA polymerase with associated mRNA 5-capping, 3-poly[A] and protein kinase activities. Observed sizes on SDS-PAGE are 150-190 10³.

G

Forms virus surface peplomers that bind to host cell (Mr ~ 65-90 10³) receptors and induce virus endocytosis and fusion. G is variously N-glycosylated; it lacks O-linked glycans. G induces and binds virus-neutralizing antibodies and elicits cell-mediated immune responses. G has hemagglutinin activity.

N

N is a major component of the viral nucleocapsid (Mr ~ 47-62 10³). It associates with full-length negative- and positive-sense RNAs, or defective RNAs, but not mRNAs. Newly synthesized N modulates genome transcription, promoting replication and read-through of transcription termination and poly[A] signals. N elicits cell-mediated immune responses and humoral antibodies.

P

A component of the viral polymerase (hence, P implies polymerase associated) (Mr ~ 20-30 10³). It is variously phosphorylated and migrates on SDS-PAGE as a Mr 40-50 10³ protein. The P of the nucleorhabdoviruses migrates faster. It is required for transcription. A soluble form is present in the cytoplasm of infected cells. It may prevent self-aggregation of N protein and aid in N encapsidation of RNA species. P elicits cell-mediated immune responses.

M

A basic protein that is an inner component of the virion (Mr ~ 20-30 10³). It is believed to regulate genome RNA transcription. M binds to nucleocapsids and the cytoplasmic domain of G, thereby facilitating the process of budding. Sometimes M is phosphorylated. M is found in the nucleus and inhibits host cell transcription.