Protein Domain : Outer capsid protein Mu1/VP4 IPR009113

Type	Family
Description	This entry includes the outer capsid protein Mu1 and VP4. Mu1 is an outer capsid protein that acts as a reoviral penetration agent. Non-enveloped animal reoviruses must enter host cells by membrane penetration that does not involve membrane fusion, as they lack a viral membrane. Reoviruses are activated by proteolytic cleavage in the intestinal lumen, leading to infectious subviral particles. The core of the virus is coated by a layer of mu1 and sigma3 proteins. Proteases strip off sigma3 exposing mu1, which provides the membrane penetration machinery that perforates the membrane. In addition, N-terminal myristoylation of polypeptide Mu1 are required for site-specific cleavage to Mu1C in transfected cells [ ]. Mu1 forms a trimer, where the three mu1 molecules are coiled around one another with a right-handed twist. The mu1 chain folds into four distinct domains: three intertwined, predominantly alpha helical domains and a jelly-roll β-sandwich []. VP4 nteracts with VP7 to form the outer icosahedral capsid with an incomplete T=13 symmetry, about 80 nm in diameter, and consisting of 200 VP4-VP7 trimers. Its myristoylated N-terminal peptide may be released in the endosome and involved in permeabilization and delivery of transcriptionally active viral particles into the host cell cytoplasm [ , ].
Short Name	Mu1/VP4