ADP-ribosylation in inner membrane of rat liver mitochondria.

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Abstract
NAD glycohydrolase activity is found at high levels in submitochondrial particles. It leads to the reaction products ADP-ribose, nicotinamide and small amounts of 5''-AMP. Furthermore, submitochondrial particles catalyze the exchange reaction: [adenosine-14C]ADP-ribose + NAD .dblarw. [adenosine-14C]NAD + ADP-ribose. When submitochondrial particles are incubated with NAD mono(ADP-ribosyl)ation of protein molecules migrating with an apparent MW of 30,000 in sodium dodecyl sulfate/polyacrylamide gel electrophoresis is demonstrable. Inhibitor studies suggest attachment of ADP-ribose to arginine residues. ADP-ribose bound to submitochondrial particles is rapidly turning over. The release of ADP-ribose from the protein is probably enzyme catalyzed. The rapid turnover, the specificity of the modification and the inhibition of ADP-ribosylation by ATP and nicotinamide suggest a regulatory role of mono(ADP-ribosyl)ation of a protein in the inner mitochondrial membrane.