Chauhan V P, Brockerhoff H
New York State Office of Mental Retardation and Developmental Disabilities, Staten Island 10314.
Biochem Biophys Res Commun. 1988 Aug 30;155(1):18-23. doi: 10.1016/s0006-291x(88)81043-x.
Phosphatidylserine/calcium-dependent protein kinase C (PKC) from rat brain is activated fifty times more efficiently by phosphatidylinositol-4,5-bisphosphate (PIP2) (Kapp = 0.04 mole% in Triton-lipid micelles) than by diacylglycerol (DG) (Kapp = 2 mole%). Both effector lipids appear to bind to the same site but PIP2 may confer a narrower substrate specificity on the kinase. DG, which together with inositol trisphosphate (IP3) is generated by hydrolysis from PIP2 after cell stimulation, has been considered the natural activator of the kinase but it is likely to be anteceded in this function by PIP2; DG may perhaps retain the function of a back-up activator. The lack of PKC-activation by phosphatidylinositol (PI) or phosphatidylinositol-4-phosphate (PIP) opens the possibility that the Inositide Shuttle, PI reversible PIP reversible PIP2, has a role in controlling the activity of the kinase.
大鼠脑磷脂酰丝氨酸/钙依赖性蛋白激酶C（PKC）被磷脂酰肌醇-4,5-二磷酸（PIP2）（在Triton脂质微团中的Kapp = 0.04摩尔%）激活的效率比被二酰基甘油（DG）（Kapp = 2摩尔%）激活的效率高50倍。两种效应脂质似乎都结合到同一位点，但PIP2可能赋予激酶更窄的底物特异性。DG与肌醇三磷酸（IP3）一起在细胞刺激后由PIP2水解产生，一直被认为是该激酶的天然激活剂，但在该功能中它可能在PIP2之后起作用；DG可能保留备用激活剂的功能。磷脂酰肌醇（PI）或磷脂酰肌醇-4-磷酸（PIP）不能激活PKC，这使得肌醇穿梭途径（PI可逆生成PIP可逆生成PIP2）有可能在控制激酶活性中发挥作用。
