Phosphatidyl inositol turnover in muscle membranes following denervation

All the enzymes necessary to synthesize and degrade PI are in the membranes, and it appears reasonable to suggest that the enhanced rate of turnover is a reflection of increased enzyme activity in denervated membranes. However, since only a small fraction of the total PI pool appears to be affected, these data can possibly be explained by an increased availability of membrane diglyceride and phosphatidic acid substrates. Small changes in other phospholipids could dramatically influence the availability of such acceptor and the subsequent rate of inositol incorporation. The authors could not rule out this possibility since addition of diglyceride or phosphatidic acid in the presence or absence of detergents had no effect, presumably because such substrates could not penetrate to a pertinent membrane site.