The virus envelope of the new coronavirus (SARS-CoV-2) contains S proteins, E proteins, and M proteins. Because S proteins are so deeply involved in the infection, so much research has been done targeting S proteins. However, very little information is available on the structure and function of M proteins. In general, the function of the M protein is understood as the protection of the viral particle structure, and it is thought that the RNA-N protein complex and the S-protein bind to the M protein, bud out as infectious particles in the small cavity, and are released out of the cell by exocytosis.
A group of King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia focused on M proteins and its differences between SARS-CoV-2, SARS-CoV, and MERS-CoV.
https://www.sciencedirect.com/science/article/pii/S1018364720304493?via%3Dihub
The following points are pointed out:
The M protein is a transmembrane protein, and there are N-terminal domain and C-terminal domain on either side of the three transmembrane domains.
From the viewpoint of the amino acid sequence, SARS-CoV-2 has an S4 residue (221-224) inserted, and it would be an unique feature of SARS-CoV-2.
As intrinsically disordered regions, there are two regions (1-7, 205-222) in SRAS-CoV-2, three regions (1-6, 207-210, 216-221) in SARS-CoV, and two regions (1-6, 216-219) in MERS-CoV, and these differences would reflect viral particles protection capability in different environments of the virus and might be related to viral transmission mode.
Domains that could be potential B-cell epitopes would be:
SARS-CoV2 183-189 ASQRVAG, 200-217 RIGNYKLNTDHSSSSDNI
SARS-CoV 183-188 SQRVGT, 199-215 RIGNYKLNTDHAGSNDN
MERS-CoV 180-188 MVKRQSYGT, 200-211 AGNYRSPPITAD