Poster: Protein targeting & vesicular trafficking
Abs #
646: A Glycoprotein α-Amylase I-1 Targets into the Plastid
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Presenter: |
Mitsui, Toshiaki , t.mitsui@agr.niigata-u.ac.jp |
Authors | Mitsui, Toshiaki (A) (B) Asatsuma, Satoru (B) (C) Yohei, Nanjo (B) (C) Okito, Mitsutoshi (A) Odagi, Yuki (B) (C) Itoh, Kimiko (B) (C) Hori, Hidetaka (C) Kato, Akira (B) (D) Hayashi, Yasuko (B) (E) Sato, Masa H. (F) Niwa, Yasuo (G) | | Affiliations: |
(A): Niigata University Department of Applied Biological Chemistry
(B): Niigata University Center for Transdisciplinary Research
(C): Niigata University Graduate School of Science and Technology
(D): Niigata University Department of Biology
(E): Niigata University Department of Environmental Science
(F): Kyoto University Graduate School of Human and Environmental Studies
(G): University of Shizuoka Graduate School of Nutritional and Environmental Sciences
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α-Amylase (EC 3.2.1.1) is the most important enzyme for starch breakdown in germinating cereal seeds. An α-amylase isoform, α-amylase I-1 encoded by RAmy1A, is actively biosynthesized and secreted in the scutellar epithelium and aleurone layer of germinating rice seed and suspension-cultured cells derived from the embryo. In addition, the α-amylase isoform I-1 is known to be a well characterized glycoprotein bearing typical N-linked oligosaccharide chain. However, our immunocytochemical analyses with specific anti-α-amylase I-1 antibodies revealed that α-amylase I-1 locates in the amyloplasts of living cells of rice, such as the scutellum and cultured cell. To provide further evidence that some α-amylase I-1 may occur in the plastid, we performed the transient and simultaneous expression of α-amylase I-1 and organelle marker fused with fluorescence protein (GFP or DsRed) in onion epidermal cell. The fluorescence-labeled α-amylase I-1 was found to be co-localized with the endoplasmic reticulum and plastid but not the mitochondrion and peroxisome markers in the onion cell. These experimental results strongly suggest that a glycoprotein α-amylase I-1 targets into the plastid.
