The incorporation of labelled phosphate into the lipids of a brain dispersion

Abstract

A simple technique was devised for preparing a lipid extract of brain tissue containing a min. of contaminating acid-soluble P. The conditions were detd. for the max. incorporation of labelled phosphate into the lipids of a guinea-pig brain dispersion. For opt. incorporation the process requires oxidizable substrate, O2, phosphate acceptor, Mg ions and cytochrome c, and is greatly accelerated by the presence of fluoride ions. Hypertonic media and low concns. of Ca ions and glucose strongly inhibit the incorporation. The use of inhibitors has shown that those which are known to uncouple oxidative phosphorylation also uncouple the respiration of a dispersion from the incorporation of labelled phosphate into its lipids. It is concluded that the initial step in the incorporation is an esterification of the P32 into high-energy phosphate compounds, which then phosphorylate phospholipid precursors.