Glucose-1-phosphate metabolism

Glycogen, a branched polymer of glucose, is a storage molecule whose accumulation is under rigorous control in many cells. In Saccharomyces cerevisiae, glycogen biosynthesis involves three processes: nucleation, elongation, and branching (also known as ramification). The formation of glycogen begins when either Glg1p or Glg2p uses UDP-glucose to self-glucosylate to produce a short alpha (1,4)-glucosyl chain covalently attached to one of their internal tyrosine residues. After the self-glucosylation of Glg1p or Glg2p, glycogen synthase is able to extend the linear alpha (1,4)-glucosyl chains of glycogen by catalyzing the formation of alpha (1,4)-glucosidic bonds from UDP- glucose at the non-reducing ends. Branches can be added into the glycogen molecule by Glc3p, which is the glycogen branching enzyme (EC:2.4.1.18) in S. cerevisiae.

肝糖原，一种由葡萄糖组成的分支聚合物，作为一种储存分子，其在众多细胞中的积累受到严格的调控。在酿酒酵母（Saccharomyces cerevisiae）中，肝糖原的生物合成涉及三个过程：成核、延长和分支（亦称分叉）。肝糖原的形成始于 Glg1p 或 Glg2p 利用 UDP-葡萄糖进行自我葡萄糖基化，从而生成一条短小的 α-(1,4)-葡萄糖基链，该链通过共价键连接至其内部的酪氨酸残基之一。Glg1p 或 Glg2p 的自我葡萄糖基化完成后，肝糖原合成酶便能够通过催化从 UDP-葡萄糖中形成 α-(1,4)-葡萄糖苷键，从而延长肝糖原的线性 α-(1,4)-葡萄糖基链。分支酶 Glc3p，即酿酒酵母中的肝糖原分支酶（EC:2.4.1.18），可以将分支添加到肝糖原分子中。