PHOSPHOINOSITIDES IN NORMAL AND ABNORMAL HUMAN RED CELLS

在人类红细胞中，磷脂酰肌醇被磷酸化为 磷脂酰肌醇磷酸(PI-P)和 磷脂酰肌醇-4，5-二磷酸(PI-P2)通过两个三磷酸腺苷依赖的激酶 反应；这些磷酸化的衍生物被转化回 磷脂酰肌醇由磷酸盐组成，仅有部分描述。 这种磷酸化/去磷酸化循环被认为与 维持红细胞形状，膜蛋白流动性，并作为一种 红细胞三磷酸腺苷的重要消费者。这项提案的目标包括 了解磷脂酰肌醇的酶学性质 正常人和高血压病患者红细胞的磷酸化/去磷酸化 患有溶血性贫血的患者。具体目标包括净化和 磷脂酰肌醇激酶的特性.特性 磷脂酰肌醇磷酸激酶；以及磷酸酶的检测 负责降解PI-P和PI-P2的活性。这个 这些肌醇磷脂在红细胞中的生理功能 也是这项提案的一个主要焦点。PI-P和PI-P2的水解性 导致这些细胞形成棘细胞。 而不是普通的双凹盘。这些发现将扩展到 确定肌醇磷脂在维持心脏功能中的重要性 由红细胞决定的细胞形状。这将包括对效应器的研究 修改PI-P和PI-P2的水平以及检查 肌醇磷脂与红细胞细胞骨架的相互作用。在……里面 此外，据报道，高达70%的净ATP被 红细胞可能被消耗在磷脂酰肌醇中 磷酸化/去磷酸化循环；这些发现将被检验以 确定如此大规模的ATP利用率对此有何影响 周而复始。溶血性贫血患者的红细胞正在进行筛查 对于涉及磷脂酰肌醇代谢途径的异常； 这些患者将非常有用地描绘出生理上的 肌醇磷脂的功能。

In the human erythrocyte, phosphatidylinositol is phosphorylated to phosphatidylinositol phosphate (PI-P) and phosphatidylinositol-4,5-Biphosphate (PI-P2) by two ATP dependent kinase reactions; these phosphorylated derivatives are converted back to phosphatidylinositol by phosphates which are only partially described. This phosphorylation/dephosphorylation cycle has been implicated in the maintenance of red cell shape, membrane protein mobility, and as a significant consumer of red cell ATP. The goals of this proposal involve understanding the enzymology of phosphatidylinositol phosphorylation/dephosphorylation in the red cells of normals and of patients with hemolytic anemia. Specific goals include purification and characterization of phosphatidylinositol kinase; characterization of phosphatidylinositol phosphate kinase; and examination of the phosphatase activities responsible for the degradation of PI-P and PI-P2. The physiological function of these phosphoinositides in the erythrocyte will also be a major focal point of this proposal. Hydrolysis of PI-P and PI-P2 in the erythrocyte results in the formation of echinocytes from these cells rather than the normal biconcave discs. These findings will be extended to determine the importance of phosphoinositides in the maintenance of cellular shape by erythrocytes. This will include the study of effectors which modify the levels of PI-P and PI-P2 as well as examination of the interaction of phosphoinositides with the erythrocyte cytoskeleton. In addition, it has been reported that up to 70% of the net ATP utilized by the erythrocyte may be consumed in the phosphatidylinositol phosphorylation/dephosphorylation cycle; these findings will be examined to determine the implications of such a massive ATP utilization for this cycle. Erythrocytes from patients with hemolytic anemia are being screened for abnormalities involved in the phosphatidylinositol metabolism pathways; these patients will be very useful in delineating the physiological function of phosphoinositides.