Characterization of rainbow trout C-polysaccharide binding proteins.

Two proteins were isolated from rainbow trout sera by affinity chromatography using C-polysaccharide-Sepharose 4B column. One was appropriate to the trout C-reactive protein (CRP) that was reported previously (Murai et al. 1990. Dev. Comp. Immunol. 14: 49-58). The other was a newly found protein that had apparent molecular weight of 135,000 on native gradient polyacrylamide gel electrophoresis, and isoelectric points of 5.2-5.8. The N-terminal sequence (twenty amino acids) of the newly found protein was similar to CRPs from other species (e.g. 44% homology with plaice CRP). On electron microscope, the newly found protein was observed as pentagonal symmetry structure.