Glycan chains play a role in the axonemal cytoskeleton disassembly activity of the 35 kDa glycoprotein of the spermathecal extract of Eyprepocnemis plorans (Insecta, Orthoptera)

In a previous study we found that a glycoprotein (gp 35), purified from spermathecal extract of the orthopteran Eyprepocnemis plorans, induced a disassembly process of the flagellum similar to that observed in some of the sperm stored in the spermatheca in 95% of the sperm tested (Giuffrida et al., 1996). In the present study the glycan chains of the protein were analysed by means of lectins and carbohydrate composition by high performance anion-exchange chromatography. The gp 35 was found to bear O- and N-linked glycans. The presence of mannose in the monosaccharide composition, as well as the negativity of the protein to ConA, suggested that the N-linked chains were of the complex tri- or tetra-antennary type. The protein was positive to RCA, DSA and LTA thus suggesting the presence of terminal residues of galactose and fucose. The role of the glycan chains in the protein activity was investigated by deglycosylating gp 35 with trifluoromethanesulfonic acid (TFMSA) and using different carbohydrates in competition assays. The results showed that the deglycosylated protein is inactive and that galactose is the only sugar able to reduce the native protein activity to approximately 50%.