CaM　BP－10对NAD激酶的抑制效应

Inhibition of NAD Kinase by CaM BP-10

ＮＡＤ激酶在光合作用等植物生理过程中起重要作用。ＮＡＤ激酶的激活依赖于钙离子和钙调素（ＣａｌｍＯｄｕｌｉｎ，ＣａＭ）．从植物中分离得到的一种新的ＣａＭ结合蛋白ＣａＭＢＰ－１０（ＢＰ－１０）明显抑制ＮＡＤ激酶的激活活性，抑制作用可被ＣａＭ所克服．动力学研究表明，抑制效应是ＢＰ－１０与ＣａＭ之间特异性相互作用的结果。实验证实ＢＰ－１０对ＮＡＤ激酶活性起着重要调节作用．

NAD kinase plays very important role in plant physiological processes,such as photosynthesis.The activation of NAD kinase is calcium and calmodulin(CaM) dependent.In preliminary studies of this laboratory,a novel plant CaM binding protein termed CaM BP-10(BP-10) was isolated.The present studies show the evidence that BP-10 specifically counteracts activated NAD kinase activity and the inhibition can be overcome by higher concentration of CaM.For the further study of the interaction between BP-10 and CaM,the kinetics of the antagonism has been investigated.It shows that concentration of BP-10 required for I50% appeared to be linearly dependent on the concentration of CaM and there also appeared to be a linear relationship between the concentration of BP-10 and the amount of CaM required for A50%.These results suggested the existence of a stoichiometric interaction betweenthe two protein effectors and it implied that the NAD kinase activity was also regulated by BP-10.