title: Tightly bound 2-azido-adenine nucleotides at catalytic and noncatalytic sites of the rat liver F1 ATPase label adjacent tryptic peptides of the beta subunit.
abstract: UV irradiation of rat liver F1 ATPase, previously exposed to Mg2+ and [beta, gamma-32P]-2-azido-ATP and separated from medium nucleotides, covalently modifies two tyrosine residues in adjacent tryptic peptides of the beta subunit. This results from the occupancy by 2-azido-ATP or 2-azido-ADP of two distinct types of nucleotide binding sites, the catalytic and noncatalytic sites. The two modified peptides are identical to the ones modified by 2-azido-adenine nucleotides in the beef heart F1 ATPase. Both catalytic and noncatalytic sites are labeled when the ATPase is exposed to [beta-32P]-2-azido-ADP in the presence or the absence of 5'-adenylyimidodiphosphate (AMP-PNP), showing that two distinct types of ADP binding sites are present on the liver enzyme. Similar incorporation of 2-azido-adenine nucleotides is obtained when membrane-bound rat liver F1 ATPase is incubated with Mg2+ and [beta, gamma-32P]-2-azido-ATP.
mesh_terms: D000244:Adenosine Diphosphate / Q000031:analogs & derivatives* / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism; D000345:Affinity Labels / Q000378:metabolism*; D000818:Animals; D001386:Azides / Q000378:metabolism*; D001665:Binding Sites; D002417:Cattle; D046911:Macromolecular Substances; D008297:Male; D008929:Mitochondria, Heart / Q000201:enzymology*; D008930:Mitochondria, Liver / Q000201:enzymology*; D010446:Peptide Fragments / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014357:Trypsin
chemical_list: D000345:Affinity Labels; D001386:Azides; D046911:Macromolecular Substances; D010446:Peptide Fragments; D000244:Adenosine Diphosphate; C022295:2-azidoadenosine 3',5'-diphosphate; C042231:2-azidoadenosine 5'-triphosphate; D000255:Adenosine Triphosphate; D014357:Trypsin; D006180:Proton-Translocating ATPases