Zancani M, Casolo V, Peresson C, Federici G, Urbani A, Macrì F, Vianello A. The β-subunit of pea stem mitochondrial ATP synthase exhibits PPiase activity.
Mitochondrion 2003;
3:111-8. [PMID:
16120349 DOI:
10.1016/s1567-7249(03)00105-3]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2003] [Revised: 07/08/2003] [Accepted: 07/29/2003] [Indexed: 11/23/2022]
Abstract
A soluble protein with a molecular mass of 55 kDa has been purified from etiolated pea stem mitochondria. The protein exhibits a Mg2+-requiring PPiase activity, with an optimum at pH 9.0, which is not stimulated by monovalent cations, but inhibited by F-, Ca2+, aminomethylenediphosphate and imidodiphosphate. The protein does not cross-react with polyclonal antibodies raised against vacuolar, mitochondrial or soluble PPiases, respectively. Conversely, it cross-reacts with an antibody for the alpha/beta-subunit of the ATP synthase from beef heart mitochondria. The purified protein has been analyzed by MALDI-TOF mass spectrometry and the results, covering the 30% of assigned sequence, indicate that it corresponds to the beta-subunit of the ATP synthase of pea mitochondria. It is suggested that this enzymatic protein may perform a dual function as soluble PPiase or as subunit of the more complex ATP synthase.
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