Refined structure of chicken skeletal muscle troponin C in the two-calcium state at 2-A resolution.

Satyshur, K.A.; Rao, S.T.; Pyżalska, D.; Drendel, William B.; Greaser, Marion L.; Sundaralingam, M.

doi:10.1016/s0021-9258(19)77925-3

Cited by 273 publications

(116 citation statements)

References 34 publications

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“…In this open state, the wide interior hydrophobic surface in each lobe is exposed. As expected, the Ca 2+ 4 -bound TnC structures differ from the Ca 2+ 2bound TnC structure [2,4] in the conformation of the N lobe. In the Ca 2+ 2 -bound TnC structure, the angles between the incoming and outgoing helices of each domain are about 140°and, because the helices pack close to one another, the hydrophobic surface is largely internalized leading to a closed conformation.…”

Section: Overall Structure Descriptionsupporting

confidence: 77%

“…There is a major difference, however, in the stabilization of the central helix when one compares the closed [2,4] and open forms of TnC (either of structures of rabbit TnC described in this study). In the closed state of the N lobe, the B and C helices, as well as the linker between them, make numerous van der Waals contacts (about 40) as well as eight specific hydrogen bonds with the central helix, in the D-helix region between residues M78-D86.…”

Section: Central Helixmentioning

confidence: 92%

“…In the C2 crystal form, the lobe is much less open than in the P2 1 2 1 2 1 crystal form. The open C lobe of avian Ca 2+ 2bound TnC [2,4] is in a position that is intermediate between the C lobes of the two crystal forms of rabbit TnC (see inter-helical angles E-F, F-G, F-H and G-H in Table 1). Superimposition of the C lobes of avian TnC onto the C lobes of the two crystal forms of rabbit TnC gives rms differences in the Cα atoms of 1.4 Å for the C2 crystal form and 1.2 Å for the P2 1 2 1 2 1 crystal form.…”

Section: The C Lobe Of Tncmentioning

confidence: 99%

“…Even in the crystal structures, there is evidence for some flexibility of this helix, although the B factors are not especially high in this region. In the two Ca 2+ 2 -TnC structures [2,4] and in the P2 1 2 1 2 1 form of the rabbit Ca 2+ 4 -TnC, the helix is similarly bent. But in the C2 crystal form of rabbit Ca 2+ 4 -TnC, due to specific packing contacts, it is bent differently, and this bending alters the relative positions of the two lobes of TnC (Figure 3).…”

Section: Central Helixmentioning

confidence: 99%

“…This class of EFhand proteins (see below) also includes the regulatory and essential light chains of myosin. High resolution crystal structures of TnC [1][2][3][4] and CaM [5][6][7] have shown that both of these very similar molecules consists of two lobes joined by a linker. Each lobe comprises two helix-loop-helix Ca 2+ -binding domains called EF hands [8].…”

Section: Introductionmentioning

confidence: 99%

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Structures of four Ca2+-bound troponin C at 2.0 Å resolution: further insights into the Ca2+-switch in the calmodulin superfamily

et al. 1997

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The two lobes of TnC are designed to respond to Ca2+-binding quite differently, although the structures with bound Ca2+ are very similar. A small number of differences in the sequences of these two lobes accounts for the fact that the C lobe is stabilized only in the open (Ca2+-bound) state, whereas the N lobe can switch between two stable states. This difference accounts for the Ca2+-dependent and Ca2+-independent interactions of the N and C lobe. The C lobe of TnC is always linked to TnI, whereas the N lobe can maintain its regulatory role - binding strongly to TnI at critical levels of Ca2+ - and in contrast, forming a stable closed conformation in the absence of Ca2+.

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Section: Overall Structure Descriptionsupporting

confidence: 77%

Section: Central Helixmentioning

confidence: 92%

Section: The C Lobe Of Tncmentioning

confidence: 99%

Section: Central Helixmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Structures of four Ca2+-bound troponin C at 2.0 Å resolution: further insights into the Ca2+-switch in the calmodulin superfamily

et al. 1997

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Amplitude and frequency dissociation spectra of ion-protein complexes rotating in magnetic fields

Binhi

2000

Bioelectromagnetics

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A mechanism is presented that predicts new biological effects of static and sinusoidal weak magnetic fields. The model is based on an earlier proposed interference mechanism of quantum states of ions within protein cavities. The quantum dynamics of an ion is studied for the case of ion–protein complexes that rotate in magnetic fields. Both the individual molecular rotation and rotation together with a biological sample are taken into account. A formula is derived for the magnetic field‐dependent part of the dissociation probability of an ion–protein in these conditions. The formula explains the unusual amplitude dependence of the known biological effect in PC‐12 cells exposed to AC–DC magnetic field. The dependence had the functional motif J21(2HAC/HDC), where J1 is the first order Bessel function of the first kind. A good fit was obtained assuming individual rotation of the Li–protein complex in MF. The macroscopic rotation of a biological system, even at low speed 1.5–2 Hz, is predicted to reduce the biological effects of a “magnetic vacuum” and to shift the spectral peaks in the field and frequency dependencies of some magnetobiological effects. Bioelectromagnetics 21:34–45, 2000. © 2000 Wiley‐Liss, Inc.

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TroponinC

Gagn��

2004

Handbook of Metalloproteins

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Regulation of contraction in skeletal and cardiac muscle occurs through calcium binding to the protein troponin C (TnC). The N‐terminal domain of TnC (NTnC) carries out the regulatory role through the binding of calcium ions – two calcium ions in skeletal muscle and one in cardiac muscle. Thirty‐nine sequences of TnC have been sequenced so far. Of the 39 sequences of TnC, 5 have had their three‐dimensional structures determined in various forms by NMR and X‐ray. Available structures include 26 uncomplexed structures in various calcium states, and 13 structures in which cardiac and skeletal TnC is complexed with fragments of troponin I and/or troponin T.

show abstract

Refined structure of chicken skeletal muscle troponin C in the two-calcium state at 2-A resolution.

Cited by 273 publications

References 34 publications

Structures of four Ca2+-bound troponin C at 2.0 Å resolution: further insights into the Ca2+-switch in the calmodulin superfamily

Structures of four Ca2+-bound troponin C at 2.0 Å resolution: further insights into the Ca2+-switch in the calmodulin superfamily

Amplitude and frequency dissociation spectra of ion-protein complexes rotating in magnetic fields

TroponinC

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