Winter H, Huber J L, Huber S C
U.S. Department of Agriculture, Agricultural Research Service, Raleigh, NC, USA.
FEBS Lett. 1997 Dec 29;420(2-3):151-5. doi: 10.1016/s0014-5793(97)01506-8.
Sucrose synthase (SuSy) plays an important role in sucrose degradation and occurs both as a soluble and as a membrane-associated enzyme in higher plants. We show that membrane association can vary in vivo in response to gravistimulation, apparently involving SuSy dephosphorylation, and is a reversible process in vitro. Phosphorylation of SuSy has little effect on its activity but decreases its surface hydrophobicity as reported with the fluorescent probe bis-ANS. We postulate that phosphorylation of SuSy (and perhaps other membrane proteins) is involved in the release of the membrane-bound enzyme in part as a result of decreased surface hydrophobicity.
蔗糖合酶（SuSy）在蔗糖降解过程中发挥着重要作用，在高等植物中以可溶性酶和膜结合酶两种形式存在。我们发现，膜结合情况在体内会因重力刺激而发生变化，这显然涉及蔗糖合酶的去磷酸化，并且在体外是一个可逆过程。蔗糖合酶的磷酸化对其活性影响不大，但如荧光探针双-ANS所示，会降低其表面疏水性。我们推测，蔗糖合酶（或许还有其他膜蛋白）的磷酸化参与了膜结合酶的释放，部分原因是表面疏水性降低。
