CSIRO Plant Industry, Canberra, ACT 2601, Australia.
J Sci Food Agric. 2013 Jul;93(9):2137-45. doi: 10.1002/jsfa.6019. Epub 2013 Jan 3.
Starch is synthesized in both leaves and storage tissues of plants. The role of starch syntheses and branching enzymes is well understood; however, the role of starch phosphorylase is not clear.
A gene encoding Pho1 from barley was characterized and starch phosphorylases from both developing and germinating grain were characterized and purified. Two activities were detected: one with a molecular mass of 110 kDa and the other of 95 kDa. It was demonstrated through the use of antisera that the 110 kDa activity was located in the amyloplast and could correspond to the polypeptide encoded by the Pho1 gene cloned. The 95 kDa activity was localized to the cytoplasm, most strongly expressed in germinating grain, and was classified as a Pho2-type sequence. Using RNAi technology to reduce the content of Pho1 in the grain to less than 30% of wild type did not lead to any visible phenotype, and no dramatic alterations in the structure of the starch were observed.
Two starch phosphorylase activities were identified and characterized in barley grains, and shown to be present during starch synthesis. However, their role in starch synthesis still remains to be elucidated.
淀粉在植物的叶片和贮藏组织中合成。淀粉合成酶和分支酶的作用已得到很好的理解；然而，淀粉磷酸化酶的作用尚不清楚。
从大麦中鉴定出编码 Pho1 的基因，并对发育中和萌发中的谷物中的淀粉磷酸化酶进行了表征和纯化。检测到两种活性：一种分子量为 110 kDa，另一种分子量为 95 kDa。通过使用抗血清证明，110 kDa 的活性位于淀粉体中，可能与克隆的 Pho1 基因编码的多肽相对应。95 kDa 的活性定位于细胞质中，在萌发的谷物中表达最强，被归类为 Pho2 型序列。使用 RNAi 技术将谷物中 Pho1 的含量降低到野生型的 30%以下，不会导致任何明显的表型，也不会观察到淀粉结构的剧烈改变。
在大麦籽粒中鉴定并表征了两种淀粉磷酸化酶活性，并表明它们在淀粉合成过程中存在。然而，它们在淀粉合成中的作用仍有待阐明。
