1O1C

MOLECULAR MODELS OF AVERAGED RIGOR CROSSBRIDGES FROM TOMOGRAMS OF INSECT FLIGHT MUSCLE

Summary for 1O1C

• Entry DOI: 10.2210/pdb1o1c/pdb
• Related: 1M8Q 1MVW 1O18 1O19 1O1A 1O1B
• EMDB information: 1001
• Descriptor: SKELETAL MUSCLE MYOSIN II, SKELETAL MUSCLE MYOSIN II REGULATORY LIGHT CHAIN, SKELETAL MUSCLE MYOSIN II ESSENTIAL LIGHT CHAIN, ... (4 entities in total)
• Functional Keywords: actin-myosin complex in situ in muscle, contractile protein
• Biological source: Gallus gallus (chicken); More
• Total number of polymer chains: 29
• Total formula weight: 1229838.81

Authors

Chen, L.F.,Winkler, H.,Reedy, M.K.,Reedy, M.C.,Taylor, K.A. (deposition date: 2002-11-18, release date: 2002-12-04, Last modification date: 2023-12-27)

Primary citation

Chen, L.F.,Winkler, H.,Reedy, M.K.,Reedy, M.C.,Taylor, K.A.
Molecular Modeling of Averaged Rigor Crossbridges from Tomograms of Insect Flight Muscle
J.Struct.Biol., 138:92-104, 2002

PubMed Abstract: Electron tomography, correspondence analysis, molecular model building, and real-space refinement provide detailed 3-D structures for in situ myosin crossbridges in the nucleotide-free state (rigor), thought to represent the end of the power stroke. Unaveraged tomograms from a 25-nm longitudinal section of insect flight muscle preserved native structural variation. Recurring crossbridge motifs that repeat every 38.7 nm along the actin filament were extracted from the tomogram and classified by correspondence analysis into 25 class averages, which improved the signal to noise ratio. Models based on the atomic structures of actin and of myosin subfragment 1 were rebuilt to fit 11 class averages. A real-space refinement procedure was applied to quantitatively fit the reconstructions and to minimize steric clashes between domains introduced during the fitting. These combined procedures show that no single myosin head structure can fit all the in situ crossbridges. The validity of the approach is supported by agreement of these atomic models with fluorescent probe data from vertebrate muscle as well as with data from regulatory light chain crosslinking between heads of smooth muscle heavy meromyosin when bound to actin.

PubMed: 12160705
DOI: 10.1016/S1047-8477(02)00013-8

Experimental method

ELECTRON MICROSCOPY (70 Å)