Mitochondrial ATP synthase F1-beta-subunit is a calcium-binding protein.
Mitochondrial ATP synthase is responsive to changes in cytosolic calcium concentration, but the regulatory mechanisms are unclear. Here we identified a major 52 kDa calcium-binding protein in rat enamel cells as the mitochondrial ATP synthase F1-beta-subunit. The F1-beta-subunit behaved as a low affinity and moderate capacity calcium-binding protein during comparative 45Ca overlay analyses. Equivalent behavior was shown by the F1-beta-subunit from rat liver mitochondria, but not by the homologous F1-alpha-subunit, supporting the specificity of calcium binding. Evidence that the catalytic F1-beta-subunit binds calcium specifically introduces new mechanistic possibilities for regulating ATP synthase, and thereby coordinating ATP production with demand for ATP-fuelled calcium pump activity.
Hubbard
M J
MJ
Department of Biochemistry, University of Otago, Dunedin, New Zealand. mother@otago.ac.nz
McHugh
N J
NJ
D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D004658:Enamel Organ / Q000201:enzymology; D013058:Mass Spectrometry; D008930:Mitochondria, Liver / Q000201:enzymology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D006180:Proton-Translocating ATPases / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D002135:Calcium-Binding Proteins; D006180:Proton-Translocating ATPases; D002118:Calcium