β-1,3-glucan receptor and peptidoglycan receptor are present as separate entities within insect prophenoloxidase activating system

Silkworm plasma was passed over a peptidoglycan-Sepharose 4B column or a CPB column [CPB, curdlan type polysaccharide(β-1,3-glucan) bead] in the absence of divalent cation and the effluents from the columns were named plasma-PG and plasma-CPB, respectively. Prophenoloxidase activating system in plasma-PG was triggered by β-1,3-glucan but not by peptidoglycan and the system in plasma-CPB was triggered by peptidoglycan but not by β-1,3-glucan, suggesting that the peptidoglycan-Sepharose 4B column and the CPB column remove peptidoglycan-receptor and β-1,3-glucan-receptor, respectively, from plasma. This result indicates that both receptors exist as separate entities in silkworm plasma. It is suggested that plasma-PG and plasma-CPB may be used as specific reagents to detect minute amounts of β-1,3-glucan and peptidoglycan.