“… 49 In Bombyx mori nucleopolyhedrovirus mature virions, the membrane fusion protein GP64 is secreted into the plasma membrane, retaining its signal peptide, which is required for infection. 50 , 51 , 52 Here, we found that the signal peptides containing BIg-like domains performed the cell membrane-binding function and were not cleaved. The cleavage efficiency was related to the length of the signal peptides; when the C terminus of the signal peptide was more prolonged than nine residues, the cleavage efficiency decreased, and no cleavage was observed when the C terminus was 13 residues long.…”