Relationship between vitellogenin and its related egg yolk proteins in Sakhalin taimen (Hucho perryi)

Vitellogenin (Vg) and its three egg yolk protein products, lipovitellin (Lv), phosvitin (Pv) and beta'-component, were isolated from mature female Sakhalin taimen (Hucho perryi). Vg had an apparent molecular weight of 540 kDa and appeared as a major 240 kDa band in SDS-PAGE, which resolved into two major bands (165 and 125 kDa) after reduction. The estimated molecular weights of purified Lv, Pv, and beta'-component were 330, 23, and 30 kDa, respectively. Lv appeared as a main band of 150 kDa in SDS-PAGE which resolved into two smaller bands (92 and 29 kDa) after reduction. beta'-component appeared as a 34 kDa band before and as a 17kDa band after reduction. Except for Pv, the purified proteins all reacted with an antiserum to Vg. In SDS-PAGE, Pv appeared as a 23 kDa band and a second < 6.5 kDa diffuse band. An antiserum to Pv dephosphorylated by alkaline phosphatase (Ap) was prepared. In Western blots, the antiserum reacted with dephosphorylated Pv and Vg, but not with Lv and beta'-component. This is the first immunological proof that three egg yolk proteins (Lv, Pv, and beta'-component) are derived from Vg in fish.