Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.3.14 (ATP synthase)
 7,042 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The combined use of proteolytic digestion and lactoperoxidase catalyzed labelling with [125I] applied to membrane-bound or soluble pure F1-ATPase from Micrococcus lysodeikticus has allowed us to establish the topography of its alpha, beta, gamma and delta subunits within the protein molecule and with respect to the plane of the membrane. The beta subunit is most externally located to the membrane bilayer looking towards the cytoplasmic face, a position consistent with its proposed catalytic role. The alpha and gamma subunits lie in an intermediate layer between the beta subunits and the membrane, in which the gamma subunit occupies a central position within the F1-ATPase molecule in contact with the alpha subunit. The delta subunit appears to be tightly bound to the F0 component of the ATPase complex, probably buried in the membrane bilayer. A molecular arrangement of M. lysodeikticus ATPase is proposed that, taking into account the subunit stoichiometry alpha 3 beta 3 gamma 2 delta 2 (MW 420 000), accommodates the role assigned to each subunit and most, if not all, the known properties of this bacterial energy-transducing protein.
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PMID:Topography of the subunits of Micrococcus lysodeikticus F1-ATPase. 622 69

The arrangement of the proton-translocating formate dehydrogenase of the anaerobic respiratory chain of Escherichia coli within the cytoplasmic membrane was examined by direct covalent modification with non-membrane-permeant reagents. Three methods were employed, lactoperoxidase-catalysed radioiodination, labelling with diazotized [125I] di-iodosulphanilic acid and labelling with diazobenzene [35S] sulphonate. All three procedures yield consistent with the view that the two larger subunits of the enzyme, Mr 110000 and 32000, both occupy transmembranous locations within the membrane. In each case the modification of the Ca2+ or Mg2+-activated F1-ATPase was monitored, and all reagents employed correctly located this enzyme at the cytoplasmic face of the membrane. A procedure involving agglutination with specific antibodies is described which appears to fractionate membrane vesicles of mixed orientation into two populations, one with the same membrane orientation as that of spheroplasts and the other opposite orientation.
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PMID:The organization of formate dehydrogenase in the cytoplasmic membrane of Escherichia coli. 703 6

The organization of the membrane-bound hydrogenase from Escherichia coli was studied by using two membrane-impermeant probes, diazotized [125I]di-iodosulphanilic acid and lactoperoxidase-catalysed radioiodination. The labelling pattern of the enzyme obtained from labelled spheroplasts was compared with that from predominantly inside-out membrane vesicles, after recovery of hydrogenase by immunoprecipitation. The labelling pattern of F1-ATPase was used as a control for labelling at the cytoplasmic surface throughout these experiments. Hydrogenase (mol.wt. approx. 63 000) is transmembranous. Crossed immunoelectrophoresis with anti-(membrane vesicle) immunoglobulins, coupled with successive immunoadsorption of the antiserum with spheroplasts, confirmed the location of hydrogenase at the periplasmic surface. Immunoadsorption with sonicated spheroplasts suggests that the enzyme is also exposed at the cytoplasmic surface. Inside-out vesicles were prepared by agglutination of sonicated spheroplasts, and the results of immunoadsorption using these vesicles confirms the location of hydrogenase at the cytoplasmic surface.
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PMID:The organization of hydrogenase in the cytoplasmic membrane of Escherichia coli. 703 17