9YKN
The structure of the cardiac native crossbridge in the rigor state, myosin heads with essential and regulatory light chains bound to actin molecules 6 and 7
Summary for 9YKN
| Entry DOI | 10.2210/pdb9ykn/pdb |
| EMDB information | 73055 |
| Descriptor | Actin, alpha cardiac muscle 1, Tropomyosin alpha-1 chain, Troponin T2, cardiac type, ... (8 entities in total) |
| Functional Keywords | cardiac myosin, tropomyosin, thin filament, troponin, motor protein |
| Biological source | Sus scrofa (pig) More |
| Total number of polymer chains | 13 |
| Total formula weight | 778731.82 |
| Authors | Galkin, V.E.,Risi, C.M. (deposition date: 2025-10-07, release date: 2026-07-22, Last modification date: 2026-09-02) |
| Primary citation | Risi, C.M.,Nguyen, T.,Belknap, B.,White, H.D.,Pinto, J.R.,Chase, P.B.,Galkin, V.E. The structure of the native cardiac crossbridge in the rigor state. Sci Adv, 12:eaeg1209-eaeg1209, 2026 Cited by PubMed Abstract: Cardiac contraction is driven by double-headed myosin cycling on cardiac thin filaments, where troponin-tropomyosin regulates myosin access to actin. Prior high-resolution structural studies used a single-headed myosin bound to bare actin, thereby limiting insight into coordination between myosin heads and the influence of troponin-tropomyosin on actomyosin interactions. Here, we report a high-resolution structure of the native cardiac rigor cross-bridge formed by heavy meromyosin bound to the thin filament. We show that direct communication between the two bound heads, uneven interactions between the heads and tropomyosin, and spatial constraints imposed by troponin govern myosin placement along the thin filament. Additionally, the two heads display non-equivalent motor-light chain interactions, yielding distinct lever-arm conformations indicative of asymmetric intramolecular strain. Together, these findings provide a structural framework for how the two myosin heads coordinate and how the components of the thin filament are integrated into force generation by active cross-bridges. PubMed: 42647613DOI: 10.1126/sciadv.aeg1209 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (5.3 Å) |
Structure validation
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