5NL2 | pdb_00005nl2

cryo-EM structure of the mTMEM16A ion channel at 6.6 A resolution.

ELECTRON MICROSCOPY

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Starting Model(s)

Initial Refinement Model(s)
Type	Source	Accession Code	Details
experimental model	PDB	4WIT

Refinement

RMS Deviations
Key	Refinement Restraint Deviation
f_dihedral_angle_d	4.269
f_angle_d	0.632
f_chiral_restr	0.042
f_plane_restr	0.005
f_bond_d	0.004

Sample
mTMEM16A

Specimen Preparation
Sample Aggregation State	PARTICLE
Vitrification Instrument	FEI VITROBOT MARK IV
Cryogen Name	ETHANE
Sample Vitrification Details	2.5 ul sample volume 1-5 sec blotting time

3D Reconstruction
Reconstruction Method	SINGLE PARTICLE
Number of Particles	213243
Reported Resolution (Å)	6.6
Resolution Method	FSC 0.143 CUT-OFF
Other Details
Refinement Type
Symmetry Type	POINT
Point Symmetry	C2

Map-Model Fitting and Refinement
Id	1 (4WIT)
Refinement Space
Refinement Protocol	RIGID BODY FIT
Refinement Target
Overall B Value
Fitting Procedure
Details

Data Acquisition
Detector Type	GATAN K2 SUMMIT (4k x 4k)
Electron Dose (electrons/Å**2)	80

Imaging Experiment	1
Date of Experiment
Temperature (Kelvin)
Microscope Model	FEI TITAN KRIOS
Minimum Defocus (nm)	500
Maximum Defocus (nm)	3800
Minimum Tilt Angle (degrees)
Maximum Tilt Angle (degrees)
Nominal CS	2.7
Imaging Mode	BRIGHT FIELD
Specimen Holder Model	FEI TITAN KRIOS AUTOGRID HOLDER
Nominal Magnification	37037
Calibrated Magnification	37037
Source	FIELD EMISSION GUN
Acceleration Voltage (kV)	300
Imaging Details

EM Software
Task	Software Package	Version
PARTICLE SELECTION	RELION	2
IMAGE ACQUISITION	SerialEM
CTF CORRECTION	CTFFIND	4.1.5
MODEL FITTING	Coot
MODEL REFINEMENT	PHENIX
INITIAL EULER ASSIGNMENT	RELION	2
FINAL EULER ASSIGNMENT	RELION	2
CLASSIFICATION	RELION	2
RECONSTRUCTION	RELION	2

Image Processing
CTF Correction Type	CTF Correction Details	Number of Particles Selected	Particle Selection Details
PHASE FLIPPING AND AMPLITUDE CORRECTION	The contrast transfer function (CTF) parameters were estimated on the movie frames by ctffind4.1	755348	Images showing a strong drift, higher defocus than -3.8 um or a bad CTF estimation were discarded, resulting in 4,178 images used for further analysis. Image processing was performed using the software package RELION1.4 and at a later stage RELION2.0. Approximately 4,000 particles were manually picked to generate templates for automated particle selection. Following automated picking in RELION, false positives were eliminated manually or through a first round of 2D classification resulting in 755,348 particles.