title: Interconversion between dimers and monomers of endogenous mitochondrial F1-inhibitor protein complexes and the release of the inhibitor protein. Spectroscopic characteristics of the complexes.
abstract: The F1-inhibitor protein complex (F1-IP) was purified from heart submitochondrial particles. Size exclusion chromatography of the endogenous complex showed that it contains dimers (D) and monomers (M) of F1-IP. Further chromatographic analysis showed that D and M interconvert. At high protein concentrations, the interconversion reaction is shifted toward the D species. The release of the inhibiting action of IP is faster at low than at high protein concentrations. During activation of F1, the M species accumulates through a process that is faster than the release of IP from F1. These findings indicate that the activation of F1-IP involves the transformation of D into M, which subsequently loses IP. The spectroscopic characteristics of D, M, and free F1 show that the binding of IP and dimerization modifies the fluorescence intensity of tyrosine residues and that of the single tryptophan of F1 which is far from the IP binding site.
authors.affiliation: Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, D. F., Mexico.
authors.forename: Lenin
authors.initials: L
authors.lastname: Domínguez-Ramírez
authors.forename: Georgina
authors.initials: G
authors.lastname: Garza-Ramos
authors.forename: Hugo
authors.initials: H
authors.lastname: Najera
authors.forename: Guillermo
authors.initials: G
authors.lastname: Mendoza-Hernández
authors.forename: Armando
authors.initials: A
authors.lastname: Gómez-Puyou
authors.forename: Marietta Tuena
authors.initials: MT
authors.lastname: de Gómez-Puyou
mesh_terms: D000818:Animals; D002417:Cattle; D002850:Chromatography, Gel; D019281:Dimerization; D004789:Enzyme Activation / Q000502:physiology; D005453:Fluorescence; D008929:Mitochondria, Heart / Q000201:enzymology*; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*; D000097795:ATPase Inhibitory Protein
chemical_list: D011506:Proteins; D000097795:ATPase Inhibitory Protein