Abstract
The formation of rigor complexes between the thick and thin filaments of glycerinated rabbit psoas muscle fibers causes the fibers to bind more calcium at any given level of free calcium. I studied the maximum amount of calcium bound as a function of filament overlap under rigor conditions. Fibers stretched to zero filament overlap (sarcomere length greater than 3.8 micron) bound exactly 75% as much calcium as fibers with maximum overlap. Between these extremes a linear relationship was found between maximum bound calcium and the length of the overlap zone. The results support the hypothesis that in the intact filament lattice one of the four calcium-binding sites of troponin depends for its existence on attachment between myosin and actin. In addition, the linear relation between maximum bound calcium and filament overlap is consistent with the assumption that the cooperative effect of rigor complex formation on calcium binding is limited to the binding site in the immediate vicinity of the rigor complex.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Bagshaw C. R. On the location of the divalent metal binding sites and the light chain subunits of vertebrate myosin. Biochemistry. 1977 Jan 11;16(1):59–67. doi: 10.1021/bi00620a010. [DOI] [PubMed] [Google Scholar]
- Bremel R. D., Weber A. Calcium binding to rabbit skeletal myosin under physiological conditions. Biochim Biophys Acta. 1975 Feb 17;376(2):366–374. doi: 10.1016/0005-2728(75)90028-6. [DOI] [PubMed] [Google Scholar]
- Bremel R. D., Weber A. Cooperation within actin filament in vertebrate skeletal muscle. Nat New Biol. 1972 Jul 26;238(82):97–101. doi: 10.1038/newbio238097a0. [DOI] [PubMed] [Google Scholar]
- Fuchs F. Cooperative interactions between calcium-binding sites on glycerinated muscle fibers. The influence of cross-bridge attachment. Biochim Biophys Acta. 1977 Nov 17;462(2):314–322. doi: 10.1016/0005-2728(77)90130-x. [DOI] [PubMed] [Google Scholar]
- Fuchs F. The binding of calcium to glycerinated muscle fibers in rigor. The effect of filament overlap. Biochim Biophys Acta. 1977 Apr 25;491(2):523–531. doi: 10.1016/0005-2795(77)90297-5. [DOI] [PubMed] [Google Scholar]
- Marston S., Tregear R. T. Calcium binding and the activation of fibrillar insect flight muscle. Biochim Biophys Acta. 1974 May 22;347(2):311–318. doi: 10.1016/0005-2728(74)90054-1. [DOI] [PubMed] [Google Scholar]
- PAGE S. G., HUXLEY H. E. FILAMENT LENGTHS IN STRIATED MUSCLE. J Cell Biol. 1963 Nov;19:369–390. doi: 10.1083/jcb.19.2.369. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Potter J. D., Gergely J. The calcium and magnesium binding sites on troponin and their role in the regulation of myofibrillar adenosine triphosphatase. J Biol Chem. 1975 Jun 25;250(12):4628–4633. [PubMed] [Google Scholar]
- Potter J. D. The content of troponin, tropomyosin, actin, and myosin in rabbit skeletal muscle myofibrils. Arch Biochem Biophys. 1974 Jun;162(2):436–441. doi: 10.1016/0003-9861(74)90202-1. [DOI] [PubMed] [Google Scholar]
- Solaro R. J., Bruni F. D., Gleason E. N. Effects of ionic strength on calcium binding to rabbit skeletal myofibrils, thin filaments and myosin. Biochim Biophys Acta. 1976 Nov 9;449(2):304–309. doi: 10.1016/0005-2728(76)90142-0. [DOI] [PubMed] [Google Scholar]
- Vibert P. J., Haselgrove J. C., Lowy J., Poulsen F. R. Structural changes in actin-containing filaments of muscle. J Mol Biol. 1972 Nov 28;71(3):757–767. doi: 10.1016/s0022-2836(72)80036-6. [DOI] [PubMed] [Google Scholar]
- Weber A., Murray J. M. Molecular control mechanisms in muscle contraction. Physiol Rev. 1973 Jul;53(3):612–673. doi: 10.1152/physrev.1973.53.3.612. [DOI] [PubMed] [Google Scholar]