人红细胞中磷酸肌醇4-磷酸和磷酸肌醇4,5-二磷酸代谢活性池稳态周转率的测定

Determination of the steady-state turnover rates of the metabolically active pools of phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate in human erythrocytes.

作者信息

King C E, Hawkins P T, Stephens L R, Michell R H

机构信息

Department of Biochemistry, University of Birmingham, U.K.

出版信息

Biochem J. 1989 May 1;259(3):893-6. doi: 10.1042/bj2590893.

DOI:10.1042/bj2590893

PMID:2543372

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1138600/

Abstract

When intact human erythrocytes are incubated at metabolic steady state in a chloride-free medium containing [32P]Pi, there is rapid labelling of the gamma-phosphate of ATP, followed by a slower labelling of the monoester phosphate groups of phosphatidylinositol 4-phosphate (PtdIns4P) and phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] [King, Stephens, Hawkins, Guy & Michell (1987) Biochem. J. 244, 209-217]. We have analysed the early kinetics of the labelling of these phosphate groups, in order to determine: (a) the steady-state rates of the interconversions of phosphatidylinositol, PtdIns4P and PtdIns(4,5)P2; and (b) the fractions of the total cellular complement of PtdIns4P and PtdIns(4,5)P2 that participate in this steady-state turnover. The experimental data most closely fit a pattern of PtdIns4P and PtdIns(4,5)P2 turnover in which one-quarter of the total cellular complement of each lipid is in the metabolic pool that participates in rapid metabolic turnover, with rate constants of 0.028 min-1 for the interconversion of PtdIns and PtdIns4P, and of 0.010 min-1 for the PtdIns4P/PtdIns(4,5)P2 cycle. These rate constants represent metabolic fluxes of approx. 2.1 nmol of lipid/h per ml of packed erythrocytes between PtdIns and PtdIns4P and of approx. 5.7 nmol/h per ml of cells between PtdIns4P and PtdIns(4,5)P2.

摘要

当完整的人体红细胞在含有[32P]Pi的无氯培养基中于代谢稳态下孵育时，ATP的γ-磷酸会迅速被标记，随后磷脂酰肌醇4-磷酸（PtdIns4P）和磷脂酰肌醇4,5-二磷酸[PtdIns(4,5)P2]的单酯磷酸基团被标记的速度较慢[金、斯蒂芬斯、霍金斯、盖伊和米切尔（1987年）《生物化学杂志》244卷，209 - 217页]。我们分析了这些磷酸基团标记的早期动力学，以便确定：（a）磷脂酰肌醇、PtdIns4P和PtdIns(4,5)P2相互转化的稳态速率；以及（b）参与这种稳态周转的PtdIns4P和PtdIns(4,5)P2在细胞总含量中所占的比例。实验数据最符合PtdIns4P和PtdIns(4,5)P2周转的一种模式，即每种脂质细胞总含量的四分之一处于参与快速代谢周转的代谢池中，PtdIns和PtdIns4P相互转化的速率常数为0.028 min-1，PtdIns4P/PtdIns(4,5)P2循环的速率常数为0.010 min-1。这些速率常数代表了PtdIns和PtdIns4P之间约2.1 nmol脂质/（h·ml压积红细胞）以及PtdIns4P和PtdIns(4,5)P2之间约5.7 nmol/（h·ml细胞）的代谢通量。