A 106 kDa form of aminopeptidase is a receptor for Bacillus thuringiensis CryIC delta-endotoxin in the brush border membrane of Manduca sexta

A soluble 106 kDa protein,vith aminopeptidase activity was isolated from Manduca sexta using CryIC toxin-affinity and anion-exchange chromatographies, Based on internal amino acid sequence analysis and different mobilities obtained with non-denaturing polyacrylamide gel electrophoresis, the 106 kDa aminopeptidase is distinct from a previously described 115 kDa CryIAc-binding aminopeptidase, The 106 kDa protein was preferentially precipitated by CryIC relative to CryIAc toxin. The 106 kDa form, like the 115 kDa aminopeptidase, has a cross-reacting determinant typical of a cleaved glycosyl-phosphatidylinositol (GPI) anchor, On ligand blots, CryIAc recognized membrane bound 120 and soluble 115 kDa aminopeptidases, but not the soluble 106 kDa form, The results show that CryIC and CryIAc delta-endotoxins recognize functionally related, but structurally distinct 106 kDa and 115 kDa isoforms of aminopeptidase in the M. sexta midgut. Copyright (C) 1996 Elsevier Science Ltd