Detection and Characterization of a Vacuolar Protein(VP24) in Anthocyanin Producing Cells of Sweet Potato in Suspension Culture : PROTEINS, ENZYMES AND METABOLISM : STRUCTURE AND FUNCTION OF CELLS

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Vacuoles containing large amounts of protein and anthocyanin were isolated and purified from anthocyanin-producing cultured cells of sweet potato (Ipomoea batatas). A 24 kDa protein (VP24), identified as a major protein in the isolated vacuoles, was detected by SDS-polyacrylamide gel electrophoresis. Neither VP24 nor anthocyanin was detectable in dark-cultured cells, but VP24 appeared three days after the start of irradiation with light and the level of VP24 in-creased for up to a week. High concentrations of 2,4-D markedly inhibited the accumulation of both VP24 and anthocyanin. These results indicated that the expression of VP24, which was induced by exposure to light, was closely accompanied by the accumulation of anthocyanin in the vacuoles. VP24 was recovered as an insoluble reddish precipitate after ultracentrifugation of a lysate of anthocyanin-containing vacuoles. Immunoblot analysis indicated that this vacuolar protein was distinct from sporamin, a major storage protein of sweet potato tuberous root. These results suggest that VP24 is not an integral protein of the vacuolar membrane but tends to form aggregates via interactions with anthocyanin during extraction. VP24 may be involved in the formation of intravacuolar pigmented structures that develop in vivo in the anthocyanin-containing vacuoles of sweet potato cells in culture.
日本植物生理学会の論文