Database of articles cited by EMDB/PDB/SASBDB data

Keywords
Structure methods	All X-ray diffraction NMR electron microscopy small angle scattering neutron diffraction fiber diffraction powder diffraction infrared spectroscopy EPR fluorescence transfer theoretical model Hybrid
Author
Journal
IF	>30 >20 >10 >5 all

Title	The structure of the native cardiac thin filament at systolic Ca levels.
Journal, issue, pages	Proc Natl Acad Sci U S A, Vol. 118, Issue 13, Year 2021
Publish date	Mar 30, 2021
Authors	Cristina M Risi / Ian Pepper / Betty Belknap / Maicon Landim-Vieira / Howard D White / Kelly Dryden / Jose R Pinto / P Bryant Chase / Vitold E Galkin /
PubMed Abstract	Every heartbeat relies on cyclical interactions between myosin thick and actin thin filaments orchestrated by rising and falling Ca levels. Thin filaments are comprised of two actin strands, each ...Every heartbeat relies on cyclical interactions between myosin thick and actin thin filaments orchestrated by rising and falling Ca levels. Thin filaments are comprised of two actin strands, each harboring equally separated troponin complexes, which bind Ca to move tropomyosin cables away from the myosin binding sites and, thus, activate systolic contraction. Recently, structures of thin filaments obtained at low (pCa ∼9) or high (pCa ∼3) Ca levels revealed the transition between the Ca-free and Ca-bound states. However, in working cardiac muscle, Ca levels fluctuate at intermediate values between pCa ∼6 and pCa ∼7. The structure of the thin filament at physiological Ca levels is unknown. We used cryoelectron microscopy and statistical analysis to reveal the structure of the cardiac thin filament at systolic pCa = 5.8. We show that the two strands of the thin filament consist of a mixture of regulatory units, which are composed of Ca-free, Ca-bound, or mixed (e.g., Ca free on one side and Ca bound on the other side) troponin complexes. We traced troponin complex conformations along and across individual thin filaments to directly determine the structural composition of the cardiac native thin filament at systolic Ca levels. We demonstrate that the two thin filament strands are activated stochastically with short-range cooperativity evident only on one of the two strands. Our findings suggest a mechanism by which cardiac muscle is regulated by narrow range Ca fluctuations.
External links	Proc Natl Acad Sci U S A / PubMed:33753506 / PubMed Central
Methods	EM (single particle)
Resolution	7.8 - 8.3 Å
Structure data	22964 7ko4 EMDB-22964, PDB-7ko4: Structure of cardiac native thin filament at pCa=5.8 having upper and lower troponins in Ca2+ free state Method: EM (single particle) / Resolution: 8.0 Å 22965 7ko5 EMDB-22965, PDB-7ko5: Structure of cardiac native thin filament at pCa=5.8 having upper and lower troponins in Ca2+ bound state Method: EM (single particle) / Resolution: 7.8 Å 22966 7ko7 EMDB-22966, PDB-7ko7: Structure of the native cardiac thin filament at pCa=5.8 having upper Tn in Ca2+ free state and lower Tn in Ca2+ bound state Method: EM (single particle) / Resolution: 8.3 Å 22978 7kon EMDB-22978, PDB-7kon: Structure of upper Tn Ca2+ free (rotated) and lower Tn Ca2+ bound cardiac native thin filament at pCa=5.8 Method: EM (single particle) / Resolution: 8.1 Å 22981 7kor EMDB-22981, PDB-7kor: Structure of cardiac native thin filament at pCa=5.8 having upper troponin in Ca2+ bound state and lower troponin in Ca2+ free state Method: EM (single particle) / Resolution: 7.8 Å
Source	sus scrofa (pig) Sus Scofa (pig)
Keywords	CONTRACTILE PROTEIN / tropomyosin / troponin / actin / TF / cardiac