Purification and characterization of vitellin from the ovary of kuruma prawn, Penaeus japonicus

As a first step in understanding the mechanism of vitellogenesis in the kur uma prawn Penaeus japonicus, biochemical characteristics of vitellin (Vt) w ere investigated. Vitellin was purified from vitellogenic ovary by gel filt ration and ion-exchange chromatography, and an anti-Vt antiserum was raised in rabbits. The molecular weight of the purified Vt was estimated to be 53 0 kDa by native-polyacrylamide gel electrophoresis and gel filtration. Vite llin was composed of three polypeptide subunits of 91, 128, and 186 kDa in sodium dodecylsulfate-polyacrylamide gel electrophoresis. The 91 kDa subuni t was further purified by reversed-phase high-performance liquid chromatogr aphy. A protein sequencer was used to analyze the amino-terminal amino acid sequence of the 91 kDa subunit; residues up to position 29 were identified , except for two residues at positions 10 and 14. Positive immunohistochemi cal reaction against the anti-Vt antiserum was observed in the cytoplasm of oocytes at endogenous and exogenous vitellogenesis stages.