Pseudomonas aeruginosa cytotoxin-binding protein in rabbit erythrocyte membranes : an oligomer of 28 kDa with similarity to transmembrane channel proteins

Rabbit erythrocyte membrane glycosylated 28-kDa protein was investigated in the membrane-bound as well as in the soluble state on an example of a Pseudomonas aeruginosa cytotoxin-binding component. When membranes were treated with trypsin/N-glycosidase F, a 13.5-kDa-binding active peptide residue is obtained as revealed by a ligand-blot technique after separation by SDS/PAGE under reducing conditions and electrophoretic transfer to nitrocellulose. Target-size analysis of intact membranes by radiation inactivation using 2-450 kGy gave a value of 29, 40 and 60 kDa for the binding-protein structure. This suggests that the native form of the binding peptide is associated as an oligomer. As seen in ligand-blot technique, 125I-cytotoxin binds with high affinity to water-channel integral protein CHIP28 from human erythrocyte membranes. The 20 N-terminal amino acids of the deglycosylated rabbit cytotoxin-binding protein show high similarity to transmembrane channel-like proteins.