title: NAD+-dependent ADP-ribosyltransferase in renal brush-border membranes.
abstract: Oxidized nicotinamide adenine dinucleotide (NAD+) in cytosol may interact with renal brush-border membranes (BBM) and inhibit BBM phosphate transport. The possible mechanism of interaction was investigated in the present study. Incubation of BBM with [adenine-3H]NAD+ led to acid-stable binding of 3H to the BBM, in contrast there was no binding of 14C when [carbonyl-14C]NAD+ was used. The data are consistent with an ADP-ribosylation mechanism involving transfer of ADP-ribose from NAD+ to BBM. This was confirmed by using [adenylate-32P]NAD+ and by the release of bound 32P in the form of 5'-[32P]AMP when the BBM were treated with snake venom phosphodiesterase. After gradient centrifugation of BBM the ADP-ribosyltransferase was recovered at the same density as known BBM enzymes, indicating that ADP-ribosyltransferase is an intrinsic BBM component and not a contaminant. These findings indicate that cytosolic NAD+ may be used for ADP-ribosylation of BBM proteins and that this may be a mechanism for regulating the BBM phosphate transport system.
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D002467:Cell Nucleus / Q000201:enzymology; D004492:Edetic Acid / Q000494:pharmacology; D007672:Kidney Cortex / Q000201:enzymology*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008871:Microvilli / Q000201:enzymology*; D009243:NAD / Q000378:metabolism / Q000494:pharmacology; D009536:Niacinamide / Q000494:pharmacology; D009713:Nucleotidyltransferases / Q000378:metabolism*; D011065:Poly(ADP-ribose) Polymerases; D051381:Rats; D011919:Rats, Inbred Strains; D013936:Thymidine / Q000494:pharmacology
chemical_list: D009243:NAD; D009536:Niacinamide; D004492:Edetic Acid; D011065:Poly(ADP-ribose) Polymerases; D009713:Nucleotidyltransferases; D008274:Magnesium; D013936:Thymidine