title: Myofibrillar tightly bound calcium in skeletal muscle fibers: a possible role of this cation in titin strands aggregation.
abstract: In muscle cells, part of the calcium is tightly bound to the N1- and N2-line of the sarcomere but its physiological significance was unknown. In the present work we reported the ability of a recombinant titin fragment spanning titin domains Z9 to I1 to tightly bind calcium ions with a K(d) of 0.049+/-0.004 nM. We further showed that calcium induced a spontaneous aggregation of the titin fragment and that the major aggregate is a tetramer. The implication of these findings on the organization of the six titin strands that emanate from the end of the thick filament within the I-band is discussed.
authors.affiliation: Muscle Biochemistry Group, INRA (Institut National de la Recherche Agronomique)-Theix, 63122, Saint Genès Champanelle, France.
authors.forename: Gerald
authors.initials: G
authors.lastname: Coulis
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Sentandreu
authors.forename: Nathalie
authors.initials: N
authors.lastname: Bleimling
authors.forename: Mathias
authors.initials: M
authors.lastname: Gautel
authors.forename: Yves
authors.initials: Y
authors.lastname: Benyamin
authors.forename: Ahmed
authors.initials: A
authors.lastname: Ouali
mesh_terms: D000595:Amino Acid Sequence; D002118:Calcium / Q000737:chemistry / Q000502:physiology*; D002412:Cations; D064211:Connectin; D008969:Molecular Sequence Data; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D009124:Muscle Proteins / Q000737:chemistry* / Q000235:genetics; D018482:Muscle, Skeletal / Q000378:metabolism*; D009210:Myofibrils / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics; D011494:Protein Kinases / Q000737:chemistry* / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D017186:Titrimetry
chemical_list: D002412:Cations; D064211:Connectin; D009124:Muscle Proteins; D010446:Peptide Fragments; D011994:Recombinant Proteins; D011494:Protein Kinases; D002118:Calcium