title: Interaction of calmodulin with the phosphofructokinase target sequence.
abstract: Ca4.calmodulin (Ca4.CaM) inhibits the glycolytic enzyme phosphofructokinase, by preventing formation of its active tetramer. Fluorescence titrations show that the affinity of complex formation of Ca4.CaM with the key 21-residue target peptide increases 1000-fold from pH 9.0 to 4.8, suggesting the involvement of histidine and carboxylic acid residues. 1H NMR pH titration indicates a marked increase in pKa of the peptide histidine on complex formation and HSQC spectra show related pH-dependent changes in the conformation of the complex. This unusually strong sensitivity of a CaM-target complex to pH suggests a potential functional role for Ca4.CaM in regulation of the glycolytic pathway.
authors.affiliation: Division of Physical Biochemistry, National Institute for Medical Research, Mill Hill, London NW7 1AA, UK.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Martin
authors.forename: Rodolfo R
authors.initials: RR
authors.lastname: Biekofsky
authors.forename: Murray A
authors.initials: MA
authors.lastname: Skinner
authors.forename: Remo
authors.initials: R
authors.lastname: Guerrini
authors.forename: Severo
authors.initials: S
authors.lastname: Salvadori
authors.forename: James
authors.initials: J
authors.lastname: Feeney
authors.forename: Peter M
authors.initials: PM
authors.lastname: Bayley
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism*; D004331:Drosophila melanogaster; D006863:Hydrogen-Ion Concentration; D019906:Nuclear Magnetic Resonance, Biomolecular; D025221:Phosphofructokinases / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D013050:Spectrometry, Fluorescence
chemical_list: D002147:Calmodulin; D011994:Recombinant Proteins; D025221:Phosphofructokinases; D002118:Calcium