Lindblom S, Ek P, Muszyńska G, Ek B, Szczegielniak J, Engström L
Department of Medical and Physiological Chemistry, Biomedical Centre, Uppsala, Sweden.
Acta Biochim Pol. 1997;44(4):809-17.
Two isoforms of sucrose synthase (SS1 and SS2) from maize (Zea mays, var. Mona) seedlings co-purified with a calcium and phospholipid dependent protein kinase. The enzymatic preparation obtained gave a positive reaction with the antibody against mammalian protein kinase C. Maize sucrose synthase was phosphorylated by the endogenous protein kinase. Also, mammalian protein kinases (protein kinase C and protein kinase A) were able to phosphorylate the 86 kDa subunit of sucrose synthase. When excised seedlings were fed [32P]orthophosphate, sucrose synthase was also phosphorylated. Microsequencing of in vivo labelled enzyme has shown phosphorylation of Ser-15 in SS2. The present work provides evidence that maize sucrose synthase is the physiological substrate of the endogenous calcium and phospholipid dependent protein kinase(s).
来自玉米(Zea mays,品种Mona)幼苗的两种蔗糖合酶同工型(SS1和SS2)与一种钙和磷脂依赖性蛋白激酶共同纯化。得到的酶制剂与抗哺乳动物蛋白激酶C的抗体产生阳性反应。玉米蔗糖合酶被内源性蛋白激酶磷酸化。此外,哺乳动物蛋白激酶(蛋白激酶C和蛋白激酶A)能够使蔗糖合酶的86 kDa亚基磷酸化。当给切除的幼苗饲喂[32P]正磷酸盐时,蔗糖合酶也被磷酸化。对体内标记酶的微量测序表明SS2中的Ser-15发生了磷酸化。本研究提供了证据表明玉米蔗糖合酶是内源性钙和磷脂依赖性蛋白激酶的生理底物。