Recombinant Influenza B virus Matrix protein 2 (M), partial

Forms presumably a highly low-pH gated proton-selective channel. Trp-23 may function as a minimalistic gate that opens and closes the pore. When the environmental pH is lower than a threshold, the BM2 channel would be activated and selectively transport protons across the membrane from the extracellular side to the cytoplasmic side. Crucial for the uncoating process. When the virion is internalized into the endosome, the channel acidifies the virion's interior, promoting the dissociation of matrix protein 1 (M1) from the ribonucleoprotein (RNP) thus allowing the transport of the RNP from the virion into the cell's nucleus. Also plays a role in viral protein secretory pathway. Elevates the intravesicular pH of normally acidic compartments, such as trans-Golgi network, preventing newly formed hemagglutinin from premature switching to the fusion-active conformation. Plays a crucial role in virion assembly. Expressed in the late phase of the infection.