betacoronavirus-specific marker of non-structural protein 3 from murine hepatitis virus and betacoronavirus in the A lineage
This model represents the betacoronavirus-specific marker (betaSM), also called group 2-specific marker (G2M), of non-structural protein 3 (Nsp3) from betacoronavirus in the embecovirus subgenus (A lineage), including murine hepatitis virus (MHV) and Human coronavirus HKU1. The betaSM/G2M is located C-terminal to the nucleic acid-binding (NAB) domain. This region is absent in alpha- and deltacoronavirus Nsp3; there is a gammacoronavirus-specific marker (gammaSM) at this position in gammacoronavirus Nsp3. Nsp3 is a large multi-functional multi-domain protein that is an essential component of the replication/transcription complex (RTC), which carries out RNA synthesis, RNA processing, and interference with the host cell innate immune system. Little is known about the betaSM/G2M domain; it is predicted to be non-enzymatic and may be an intrinsically disordered region. The betaSM/G2M domain is part of the predicted PLnc domain (made up of 385 amino acids) of the related SARS-CoV Nsp3 that may function as a replication/transcription scaffold, with interactions to Nsp5, Nsp12, Nsp13, Nsp14, and Nsp16.