6X5Z

Bovine Cardiac Myosin in Complex with Chicken Skeletal Actin and Human Cardiac Tropomyosin in the Rigor State

ELECTRON MICROSCOPY

Sample
Helical complex of bovine S1 cardiac myosin and human cardiac tropomyosin-decorated chicken skeletal actin filaments
Sample Components
skeletal actin filaments
S1 cardiac myosin
cardiac tropomyosin

Specimen Preparation
Sample Aggregation State	HELICAL ARRAY
Vitrification Instrument	FEI VITROBOT MARK III
Cryogen Name	ETHANE
Sample Vitrification Details	Thin filaments were reconstituted by first mixing F-actin and tropomyosin to final concentrations of 10 uM actin and 7 uM tropomyosin. Just before app ...	Thin filaments were reconstituted by first mixing F-actin and tropomyosin to final concentrations of 10 uM actin and 7 uM tropomyosin. Just before applying 1.5 uL actin-tropomyosin to a freshly glow discharged holey-carbon grid, the surfactant octyl B-D-glucopyranoside was added to the protein solution to a concentration of 12 nM. The grid sample was manually blotted for 1 second and a 1.5 uL drop of 7.5 uM myosin-S1 sub-fragment was then applied to the blotted grid sample. The sample was immediately blotted for 4 seconds and plunge-frozen in liquid ethane.

3D Reconstruction
Reconstruction Method	HELICAL
Number of Particles	32158
Reported Resolution (Å)	4.24
Resolution Method	FSC 0.143 CUT-OFF
Other Details	Performed in the Relion post-processing step
Refinement Type
Symmetry Type	HELICAL
Axial Symmetry	C1
Axial Rise	27.5
Angular Rotation	-166.4

Map-Model Fitting and Refinement
Id	1 (6KN8, 3I5G)	2	3
Refinement Space	REAL	REAL	REAL
Refinement Protocol	FLEXIBLE FIT	OTHER	OTHER
Refinement Target
Overall B Value		70.88
Fitting Procedure	flexible fitting	real space refinement	manual refinement
Details	version 1.9.3; initial flexible fitting to align secondary structure using MDFF	version 1.18-3861	manual refinement of residues to match backbone and sidechain density and to limit clashes, sidechain outliers, and Ramachandran outliers

Data Acquisition
Detector Type	GATAN K2 SUMMIT (4k x 4k)
Electron Dose (electrons/Å**2)	53

Imaging Experiment	1
Date of Experiment
Temperature (Kelvin)
Microscope Model	FEI TITAN KRIOS
Minimum Defocus (nm)	1500
Maximum Defocus (nm)	2500
Minimum Tilt Angle (degrees)
Maximum Tilt Angle (degrees)
Nominal CS
Imaging Mode	BRIGHT FIELD
Specimen Holder Model	FEI TITAN KRIOS AUTOGRID HOLDER
Nominal Magnification
Calibrated Magnification	130000
Source	FIELD EMISSION GUN
Acceleration Voltage (kV)	300
Imaging Details

EM Software
Task	Software Package	Version
PARTICLE SELECTION	RELION	3.0.7
IMAGE ACQUISITION	EPU
CTF CORRECTION	CTFFIND	4.1
INITIAL EULER ASSIGNMENT	RELION	3.0.7
FINAL EULER ASSIGNMENT	RELION	3.0.7
RECONSTRUCTION	RELION

Image Processing
CTF Correction Type	CTF Correction Details	Number of Particles Selected	Particle Selection Details
PHASE FLIPPING AND AMPLITUDE CORRECTION		45040

RCSB PDB Core Operations are funded by the National Science Foundation (DBI-1832184), the US Department of Energy (DE-SC0019749), and the National Cancer Institute, National Institute of Allergy and Infectious Diseases, and National Institute of General Medical Sciences of the National Institutes of Health under grant R01GM133198.