Characterization of yolk proteins from the eggs of the indian meal moth, Plodia interpunctella

Abstract

The eggs of the Indian meal moth, Plodia interpunctella (Hübner), contain four major yolk polypeptides (YPs). The four YPs were associated as two proteins that lacked immunocrossreactivity either as native proteins or as individual polypeptide subunits. Vitellin was found to be a glycolipoprotein composed of YP1 (153 kDa) and YP3 (43 kDa) and had an apparent molecular mass ranging from 398 to 475 kDa as established by various methods. The other major yolk protein was composed of glycosylated polypeptides YP2 and YP4 that were produced by ovarian tissues. Two forms of YP2/YP4 were observed under native conditions that had molecular masses of 93 and 235 kDa in pore-limited gel electrophoresis. The heterogeneity of the protein may be due to proteolytic cleavage of YP2 by endogenous proteases, since polypeptides of 50 and 60 kDa appeared in solutions containing partially purified YP2/YP4, and these smaller polypeptides were shown to be related to YP2 by peptide mapping. Thus, the yolk of P. interpunctella was found to contain two major yolk proteins; vitellin was identified as well as a large multiple submit protein produced within the ovary that was unlike any previously described yolk protein from moths.