The matrix 2 M2 protein is a proton-selective ion channel protein, integral in the viral envelope of the influenza A virus. The channel itself is a homotetramer (consists of four identical M2 units), where the units are helices stabilized by two disulfide bonds. It is activated by low pH. M2 protein is encoded on the seventh RNA segment together with the matrix protein M1. Proton conductance by the M2 protein in influenza A is essential for viral replication
Matrix 2 cDNAs
The influenza virus M2 protein is a 97-amino-acid integral membrane protein that forms disulfide-linked tetramers. M2 is predominantly associated with its wellcharacterized proton channel activity. During the virus entry process, this activity allows for the acidification of the virion interior, which permits vRNP release from M1.
• The C-terminal 54 amino acids of M2: Form the highly conserved cytoplasmic tail, which is important for both the assembly and budding processes but has little effect on the M2 proton channel activity. The membrane-distal region of the cytoplasmic tail has been shown to be critical for the incorporation of vRNPs into budding particles.
• The membrane-proximal region of M2 : Induce membrane curvature and has been implicated in ESCRT-independent membrane scission and budding of IAV particles.
The influenza A virus (IAV) M2 protein is a multifunctional protein with critical roles in virion entry, assembly, and budding. M2 is targeted to the apical plasma membrane of polarized epithelial cells, and the interaction of the viral proteins M2, M1, HA, and NA near glycolipid rafts in the apical plasma membrane is hypothesized to coordinate the assembly of infectious virus particles.
• Nicholas Wohlgemuth. Influenza A Virus M2 Protein Apical Targeting Is Required for Efficient Virus Replication.Journal of Virology.2018
• Kolpe A.M2-based influenza vaccines: recent advances and clinical potential.Expert Rev Vaccines. 2017