Purification and properties of a 35 kDa glycoprotein from spermathecal extract of eyprepocnemis plorans (insecta, orthoptera) with axonemal cytoskeleton disassembly activity

A glycoprotein (gp35) was purified from spermathecal extract of the orthopteran Eyprepocnemis plorans by FPLC gel filtration. Using an in vitro assay, this protein was found to be the only spermathecal extract component capable of inducing modifications of the sperm flagellum similar to those observed in vivo. This biological activity is achieved during the course of sexual maturation. Intact gp35 migrated in SDS-PAGE as a doublet with 34 and 36 kDa components, becoming a single band after complete deglycosylation. The protein also has a unique N-terminus. Chemical deglycosylation revealed that the carbohydrate component accounts for about 10% of the total protein mass. Its pI was found to be slightly acidic. Radiolabeled gp35 bound the sperm surface with typical receptor-ligand kinetics.