Myofibrillar tightly bound calcium in skeletal muscle fibers: a possible role of this cation in titin strands aggregation.
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.
Coulis
Gerald
G
Muscle Biochemistry Group, INRA (Institut National de la Recherche Agronomique)-Theix, 63122, Saint Genès Champanelle, France.
Sentandreu
Miguel A
MA
Bleimling
Nathalie
N
Gautel
Mathias
M
Benyamin
Yves
Y
Ouali
Ahmed
A
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
D002412:Cations; D064211:Connectin; D009124:Muscle Proteins; D010446:Peptide Fragments; D011994:Recombinant Proteins; D011494:Protein Kinases; D002118:Calcium