糖原的合成代谢 1. Glycogen is synthesized using UDP-glucose: ◆6-磷酸葡萄糖( from glucose phosphorylation or gluconeogenesis)首先 转化为1-磷酸葡萄糖(cata/ yzed by phosphoglucomutase),然后与UTP反应形 成 UDP-glucose(UDPG),催化该反应 的是尿嘧啶核苷二磷酸葡萄糖焦磷酸化酧 (UDP-glucose pyrophosphorylase named for the reverse reaction
二、糖原的合成代谢 1. Glycogen is synthesized using UDP-glucose： ◆ 6-磷酸葡萄糖 (from glucose phosphorylation or gluconeogenesis)首先 转化为1-磷酸葡萄糖 (catalyzed by phosphoglucomutase), 然后与UTP反应形 成 UDP-glucose（UDPG） ，催化该反应 的是尿嘧啶核苷二磷酸葡萄糖焦磷酸化酶 (UDP-glucose pyrophosphorylase named for the reverse reaction)
2. Glycogen is extended from the nonreducing end using UDP-glucose ※在糖原合成酶催化下,UDFG中的葡萄糖分子 通过α-1,4糖苷键连接到糖原引物的非还原性末 端 ※分枝的形成由分枝酶催化[ glycosy(4->6)- transferase ] a terminal fragment of 6-7 residues is transferred from a branch having at least 11 residues to the C-6 hydroxyl group at a more interior position of the same or another glycogen chain
2. Glycogen is extended from the nonreducing end using UDP-glucose • ※ 在糖原合成酶催化下，UDPG中的葡萄糖分子 通过a-1,4 糖苷键连接到糖原引物的非还原性末 端。 • ※ 分枝的形成由分枝酶催化［ glycosyl-(4→6)- transferase ］: a terminal fragment of 6-7 residues is transferred from a branch having at least 11 residues to the C-6 hydroxyl group at a more interior position of the same or another glycogen chain
※在没有糖原引物时,糖原的合成是从生 糖原蛋白质开始的。 The very first glucose residue transferred from UDP-glucose, is covalently attached to Tyr 94 of glycogenin (生糖原蛋白质),a37 kDa protein that also catalyzes the assembly of the first 8 glucose residues in a complex formed between glycogenin and glycogen synthase
• ※ 在没有糖原引物时，糖原的合成是从生 糖原蛋白质开始的。 The very first glucose residue, transferred from UDP-glucose, is covalently attached to Tyr194 of glycogenin （生糖原蛋白质）, a 37 kDa protein that also catalyzes the assembly of the first 8 glucose residues in a complex formed between glycogenin and glycogen synthase
3. Glycogen synthase and glycogen phosphorylase are reciprocally regulated in vertebrates by hormones ★糖原磷酸化酶和糖原合成酶的活性均受磷酸化 和脱磷酸( Phosphorylation and dephosphorylation)调控,但作用正好相反 x Hormones like epinephrine(acting on muscle cells) or glucagon(acting on liver cells) will activate protein kinase a, which will lead to phosphorylation modification of both the glycogen phosphorylase(thus activating it and the glycogen synthase(thus inactivating it
3. Glycogen synthase and glycogen phosphorylase are reciprocally regulated in vertebrates by hormones • ★糖原磷酸化酶和糖原合成酶的活性均受磷酸化 和脱磷酸（ Phosphorylation and dephosphorylation ）调控，但作用正好相反。 • ★ Hormones like epinephrine (acting on muscle cells) or glucagon (acting on liver cells) will activate protein kinase A, which will lead to phosphorylation modification of both the glycogen phosphorylase (thus activating it) and the glycogen synthase (thus inactivating it)
Insulin nsulin receptor ranI PI-3K kpIp PIP2-00000005 OH PDK-1 Cytosol IRS-1 L IRS. PKB Activ P GSK3 GSK3 Inactive AIOH Glycogen YP Glycogen Y-OH synthase synthase b Inactive