| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1986: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1985: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
The purpose of this study was to characterize the phosphorylation of vitellogenin and vitellin from the silkworm, Bombyx mori. The proteins were radiolabeled by injecting with <^(32)P> -orthophosphate and were analyzed by one and two dimensional SDS PAGE and autoradiography. According to the results, subunits of Vn and Egg specific protein were the major phosphoproteins in the ovary,while Vg was the only phosphoprotein in the hemolymph. The major phosphorylation of Vg occurred before secretion into the hemolymph.
The heavy and light chains of Vg and Vn were shown by chemical phosphate analysis to contain about 7.0, 8.2, 3.6 and 5.1 mole of phosphate per mole of subunit , respectively. The phosphate content of Vn subunits was higher than that of Vg subunits , indicating that additional phosphorylation occurred after uptake into the ovary, as was suggested in our previous paper.
Labeling of Vg of Bombyx silkworm by incubation of fat bodies with <^(32)P> -orthophosphate, and analysis of immunoprecipitates demonstrated the incorporation of <^(32)P> into Vg subunits. Vgs from African migratory locusts, Samia silkworm and cockroach were also phosphorylated in cultured fat bodies. The data suggest that the Vgs are phosphorylated before secretion into the hemolymph.
Together with recent findings from other laboratories, these results suggest that phosphorylation is the common and essential modification of the insect Vg. The post-translational processing of Vg from these insects is compared and possible role in vitellogenesis and trasnport mechanism of the protein is discussed.
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