The Influence of Specific Phospholipids on the Interaction of Hexokinase with the Outer Mitochondrial Membrane

Abstract

Repeated washing of a [rat] brain mitochondrial fraction results in a progressive decrease in proportion of mitochondrially bound hexokinase that can be solubilized during a subsequent incubation with G-6-P. Phospholipids removed during the washing procedure can be added back to washed mitochondria, resulting in enhancement of the solubilization by G-6-P. Column chromatgraphic and TLC methods were used to isolate and identify active phospholipids. Additional studies were performed with purified lipids obtained commercially. Both lysophospholipids and acidic phospholipids were active in enhancing solubilization of hexokinase by G-6-P. Phospho-inositides, particularly diphosphoinositide, were quite effective, raising the possibility that the actively metabolized phosphoinositides may be involved in regulation of hexokinase binding in vivo.