1.A.61.1.2
Flock House virus (FHV) capsid protein-α of 407 aas; Its C-terminal 44 aas comprise a lytic peptide, one of the γ-peptides that inserts into endomembranes forming pores. Capsid protein alpha self-assembles to form an icosahedral procapsid with a T=3 symmetry, about 30 nm in diameter, and consisting of 60 capsid proteins trimers. 240 calcium ions are incorporated per capsid during assembly. The capsid encapsulates the two genomic RNAs. Capsid maturation occurs via autoproteolytic cleavage of capsid protein alpha, generating capsid protein beta and the membrane-active peptide gamma.  Peptide γ is a membrane-permeabilizing peptide produced during virus maturation, thereby creating the infectious virion. After endocytosis into the host cell, peptide gamma is exposed in endosomes, where it permeabilizes the endosomal membrane, facilitating translocation of viral capsid or RNA into the cytoplasm.  Nangia et al. 2019 shed light on the actions of varied forms of the FHV lytic peptide including membrane insertion, trans-membrane stability, peptide oligomerization, water permeation activity and dynamic pore formation.