Purification and characterization of a putative vitellogenin from the ovary of amphioxus (Branchiostoma belcheri tsingtaunese).

An oocyte-yolk protein was purified by double-step chromatography from amphioxus ovaries. The purified protein appeared to exist as a homodimer of approximately 320 kDa in native polyacrylamide gel electrophoresis (PAGE), and was reduced to a single monomer of approximately 160 kDa in sodium dodecyl sulfate-PAGE (SDS-PAGE). The protein was characterized as a phospholipoglycoprotein by native PAGE and staining of gels for phosphorus with methyl green, for lipids with oil red O and Sudan black B, and for carbohydrates using periodic acid/Schiff reagent. In addition, the amino acid composition of the oocyte-yolk protein was generally similar to that of vitellogenins (Vgs) isolated from different phyla of animals including both vertebrates and invertebrates. The purified phospholipoglycoprotein is thus considered as putative amphioxus Vg.