Experiment: 9O51

Cryo-EM structure of the human SK2-4 chimera/calmodulin channel complex in the Ca2+ free state

ELECTRON MICROSCOPY

Starting Model(s)

Initial Refinement Model(s)
Type	Source	Accession Code	Details
experimental model	PDB	9O48

Refinement

RMS Deviations
Key	Refinement Restraint Deviation
f_dihedral_angle_d	3.03
f_angle_d	0.314
f_chiral_restr	0.033
f_plane_restr	0.002
f_bond_d	0.001

Sample
Ternary complex of human SK2-4 chimera/calmodulin channel complex in the Ca2+-free state
Sample Components
Human SK2-4 chimeric channel
Human calmodulin

Specimen Preparation
Sample Aggregation State	PARTICLE
Vitrification Instrument	FEI VITROBOT MARK IV
Cryogen Name	ETHANE
Sample Vitrification Details	5 uL of sample was applied to grids at 4 degree temperature with 100% humidity. After 30 seconds, grids were blotted for 5 seconds with blot force 25 ...	5 uL of sample was applied to grids at 4 degree temperature with 100% humidity. After 30 seconds, grids were blotted for 5 seconds with blot force 25 and plunged into liquid ethane.

3D Reconstruction
Reconstruction Method	SINGLE PARTICLE
Number of Particles	386845
Reported Resolution (Å)	3.4
Resolution Method	FSC 0.143 CUT-OFF
Other Details
Refinement Type
Symmetry Type	POINT
Point Symmetry	C4

Map-Model Fitting and Refinement
Id	1 (9O48)
Refinement Space	REAL
Refinement Protocol
Refinement Target
Overall B Value
Fitting Procedure
Details

Data Acquisition
Detector Type	FEI FALCON IV (4k x 4k)
Electron Dose (electrons/Å**2)	50

Imaging Experiment	1
Date of Experiment
Temperature (Kelvin)
Microscope Model	TFS KRIOS
Minimum Defocus (nm)	800
Maximum Defocus (nm)	1600
Minimum Tilt Angle (degrees)
Maximum Tilt Angle (degrees)
Nominal CS	0.01
Imaging Mode	BRIGHT FIELD
Specimen Holder Model	FEI TITAN KRIOS AUTOGRID HOLDER
Nominal Magnification	75000
Calibrated Magnification
Source	FIELD EMISSION GUN
Acceleration Voltage (kV)	300
Imaging Details

EM Software
Task	Software Package	Version
PARTICLE SELECTION	cryoSPARC
IMAGE ACQUISITION	EPU
MODEL FITTING	PHENIX	1.21.2_5419
INITIAL EULER ASSIGNMENT	cryoSPARC
FINAL EULER ASSIGNMENT	cryoSPARC
CLASSIFICATION	cryoSPARC
RECONSTRUCTION	cryoSPARC
MODEL REFINEMENT	PHENIX	1.21.2_5419

Image Processing
CTF Correction Type	CTF Correction Details	Number of Particles Selected	Particle Selection Details
PHASE FLIPPING AND AMPLITUDE CORRECTION		8200000