Purification of the precursors to vitelline envelope proteins from serum of Sakhalin taimen, Hucho perryi.

High and low molecular weight vitelline envelope-related proteins (hVERP and lVERP) were purified from serum of vitellogenic female Sakhalin taimen (Hucho perryi) by a combination of ion-exchange, hydroxylapatite and gel filtration chromatography. The molecular weight of hVERP was estimated to be 83 kDa by gel filtration, and 48 kDa and 54 kDa in SDS-PAGE under non-reduced and reduced conditions, respectively. The molecular weight of lVERP was 56 kDa by gel filtration, and 42 kDa and 46 kDa on SDS-PAGE (non-reduced and reduced, respectively). Amino acid composition of hVERP was characterized by high content of proline (15.9%) and glutamic acid (13.8%). The lVERP had high contents of glutamic acid (10.8%) and aspartic acid (10.5%). Specific antibodies against hVERP and against lVERP were prepared by immunizing rabbits. The antiserum to hVERP stained bands corresponding to 98 kDa and 48 kDa of vitelline envelope (VE) in SDS-PAGE without reduction, whereas the antiserum to lVERP immunostained 98 kDa and 42 kDa bands. Both specific antibodies recognized the vitelline envelope of vitellogenic oocytes immunocytochemically. Thus, hVERP and lVERP are precursors to vitelline envelope proteins in this species.