Blumenfeld M L, Krisman C R
Eur J Biochem. 1986 Apr 1;156(1):163-9. doi: 10.1111/j.1432-1033.1986.tb09562.x.
A partially purified glycogen synthase from rat cardiac muscle transferred glucosyl residues from UDP-[14C]glucose to an endogenous protein acceptor in the absence of added primer. After native gel electrophoresis of the enzyme preparation, unprimed activity was detected. Primer-dependent and independent activities were found in the same position. After denaturing gel electrophoresis of the reaction products, radioactivity comigrated with protein. Pulse-chase experiments showed that the size of the reaction products increased as a function of time. These products were degraded by amyloglucosidase, thus suggesting that glycogen-like molecules had grown on the protein acceptor. The activity of the enzyme was markedly reduced upon preincubation with alpha-amylase. Therefore, preformed protein-bound alpha-1,4-glucans were acting as primers. The glucoprotein acceptor may be a protein strongly associated with glycogen synthase, or alternatively, the enzyme itself.
从大鼠心肌中提取的部分纯化的糖原合酶，在没有添加引物的情况下，能将UDP-[14C]葡萄糖中的葡萄糖基残基转移到内源性蛋白质受体上。对酶制剂进行天然凝胶电泳后，检测到了无引物活性。在同一位置发现了引物依赖性和非依赖性活性。对反应产物进行变性凝胶电泳后，放射性与蛋白质迁移一致。脉冲追踪实验表明，反应产物的大小随时间增加。这些产物被淀粉葡糖苷酶降解，因此表明在蛋白质受体上生长了类糖原分子。用α-淀粉酶预孵育后，酶的活性显著降低。因此，预先形成的与蛋白质结合的α-1,4-葡聚糖起到了引物的作用。糖蛋白受体可能是一种与糖原合酶紧密相关的蛋白质，或者就是酶本身。
