Promoting Protein, a Silkworm Hemolymph Protein Promoting in Vitro Replication of Nucleopolyhedrovirus, Binds to β-Glucans

A protein which bound to 125I-labeled peptidoglycan (PGN) was isolated from hemolymph of silkworm larvae. The N-terminal amino acid sequence and the molecular weight of the protein were in accord with those described for Promoting Protein (PP) from the silkworm. The binding of the protein to [125I]PGN was competitively inhibited by various β-glucans. The binding kinetics of PGN and chitin to the protein were analyzed in a biosensor.