Neutron and x-ray scattering studies of the interactions between Ca{sup 2+}-binding proteins and their regulatory targets: Comparisons of troponin C and calmodulin
The regulatory proteins calmodulin and troponin C share a strikingly unusual overall structure. Their crystal structures show each protein consists of two structurally homologous globular domains connected by an extended, solvent exposed alpha-helix of = 8 turns. Calmodulin regulates a variety of enzymes that show remarkable functional and structural diversity. This diversity extends to the amino acid sequences of the calmodulin-binding domains in the target enzymes. In contrast with calodulin, troponin C appears to have a single very specialized function. It is an integral part of the troponin complex, and Ca{sup 2+} binding to troponin c results in the release of the inhibitory function of troponin I, which eventually leads to actin-binding to myosin and the triggering of muscle contraction. Small-angle scattering has been particularly useful for studying the dumbbell shaped proteins because the technique is very sensitive to changes in the relative dispositions of the two globular domains. Small-angle scattering, using x-rays or neutrons, gives information on the overall shapes of proteins in solution. Small-angle scattering studies of calmodulin and its complexes with calmodulin-binding domains from various target enzymes have played an important role in helping us understand the functional role of its unusual solvent exposed helix. Likewise, small-angle scattering has been used to study troponin C with various peptides, to shed light on the similarities and differences between calmodulin and troponin C.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- National Insts. of Health, Bethesda, MD (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 10194497
- Report Number(s):
- LA-UR-93-3851; CONF-920821-4; ON: DE94002706; TRN: 93:004517
- Resource Relation:
- Conference: 4. international conference on biophysics and synchrotron radiation,Tsukuba (Japan),30 Aug - 5 Sep 1992; Other Information: PBD: [1993]
- Country of Publication:
- United States
- Language:
- English
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