Post-translational modifications of coronavirus proteins: roles and function

Fung, To Sing; Liu, Ding Xiang

M protein is the most abundant protein in the coronavirus virion. Composing of 220-260 amino acids, this protein is a multipass transmembrane protein ( Figure 4A ), with a short N-terminal ectodomain, three hydrophobic TM domains and a large C-terminal endodomain [9, 87] . Homotypic interaction between M protein provides the scaffold for virion assembly, while heterotypic interaction recruits other structural protein and genomic RNA to the assembly site [88, 89] . The only known PTM on coronavirus M protein is glycosylation of its ectodomain, which is exclusively O-linked in some Betacoronaviruses but exclusively N-linked in other coronaviruses ( Figure 4B & Table 1 ) [90, 91] .