Xu W, Moriya K, Yamada K, Nishimura M, Shioiri H, Kojima M, Nozue M
Graduate School of Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, 386-8567, Nagano, Japan
Plant Sci. 2000 Dec 7;160(1):121-128. doi: 10.1016/s0168-9452(00)00374-5.
A 24-kDa vacuolar protein (VP24) was found to accumulate in anthocyanin-producing sweet potato cells (Ipomoea batatas Lam.) in suspension culture [Nozue et al., Plant Physiol. 115 (1997) 1065]. VP24 cDNA (accession No. AB025531) encodes a 96.3-kDa large precursor protein with a C-terminal propeptide which contains the eight putative transmembrane domains. The mature VP24 is probably involved in the formation of intravacuolar pigmented globules (cyanoplasts) in highly anthocyanin-containing vacuoles, but the biological function of the C-terminal region including the putative transmembrane domains is unknown. To confirm the expression and characterize the C-terminal region in the VP24 protein precursor in the anthocyanin-producing cells, polyclonal antibodies were developed against the fusion protein, including the C-terminal region, expressed in Escherichia coli. Western blot analysis showed that a 36-kDa peptide (VP36) localized in anthocyanin-containing vacuoles was expressed under continuous illumination, but not in darkness. The expression pattern of VP36 showed high similarity to VP24. These results suggested that VP36 may be derived from the large VP24 protein precursor; it includes several of the hydrophobic domains in the C-terminal region.
研究发现，一种24 kDa的液泡蛋白（VP24）在悬浮培养的产花青素甘薯细胞（Ipomoea batatas Lam.）中积累[野津等人，《植物生理学》115（1997）1065]。VP24 cDNA（登录号AB025531）编码一种96.3 kDa的大前体蛋白，其C末端前肽包含八个假定的跨膜结构域。成熟的VP24可能参与了富含花青素的液泡中液泡内色素小球（蓝质体）的形成，但包括假定跨膜结构域在内的C末端区域的生物学功能尚不清楚。为了在产花青素细胞中确认VP24蛋白前体中C末端区域的表达并对其进行表征，制备了针对在大肠杆菌中表达的包含C末端区域的融合蛋白的多克隆抗体。蛋白质印迹分析表明，一种定位于含花青素液泡中的36 kDa肽（VP36）在持续光照下表达，但在黑暗中不表达。VP36的表达模式与VP24高度相似。这些结果表明，VP36可能源自大的VP24蛋白前体；它在C末端区域包含几个疏水结构域。
