ELECTRON MICROSCOPY

Sample

Human inward-rectifier potassium channel 2.1 (Kir2.1)

Specimen Preperation
Sample Aggregation State PARTICLE
Vitrification Instrument FEI VITROBOT MARK III
Cryogen Name ETHANE
Sample Vitrification Details ?
3D Reconstruction
Reconstruction Method SINGLE PARTICLE
Number of Particles 63584
Reported Resolution (Å) 4.3
Resolution Method FSC 0.143 CUT-OFF
Other Details ?
Refinement Type
Symmetry Type POINT
Map-Model Fitting and Refinement
ID 1
Refinement Space REAL
Refinement Protocol OTHER
Refinement Target Correlation coefficient
Overall B Value 404.73
Fitting Procedure ?
Details For structural fitting, it was used dock-in-map (available at PHENIX) that uses both SSM and convolution-based shape searches to find a part of a map that is similar to a model. An initial in silico homology model of human Kir2.1 was generated using I-TASSER using the crystal structure of chicken Kir2.2 channel (PDB ID 3JYC) as a template. For building and refinement of the atomic model, the transmembrane domain (TMD, 55-184 region) of this in silico model was placed into the final sharpened cryo-EM map using the Dock in Map tool available in PHENIX. For the cytoplasmic domain (CTD; 188-367 region), the crystal structure of the CTD from mice Kir2.1 channel (PDB ID 1U4F) was placed into the final cryo-EM map using the same approach. Once the models were placed in the electron density, the loops that connect the two domains (185-187 region) and a N-terminal loop (41-54 region) absent in the in silico model were manually built using Coot.
Data Acquisition
Detector Type FEI FALCON III (4k x 4k)
Electron Dose (electrons/Å2) 61.7
Imaging Experiment
Date of Experiment ?
Temprature (Kelvin)
Microscope Model FEI TITAN KRIOS
Minimum Defocus (nm) 1200
Maximum Defocus (nm) 2800
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 105000
Calibrated Magnification ?
Source FIELD EMISSION GUN
Acceleration Voltage (kV) 300
Imaging Details ?
Imaging Experiment
Task Software Package Version
PARTICLE SELECTION crYOLO 1.6
IMAGE ACQUISITION EPU ?
CTF CORRECTION CTFFIND 4
MODEL FITTING PHENIX 1.20
MODEL REFINEMENT PHENIX 1.20
MODEL REFINEMENT Coot 0.9.7
INITIAL EULER ASSIGNMENT RELION 3.0.7
FINAL EULER ASSIGNMENT RELION 3.0.7
CLASSIFICATION RELION 3.0.7
RECONSTRUCTION RELION 3.0.7
Image Processing
CTF Correction Type CTF Correction Details Number of Particles Selected Particle Selection Details
PHASE FLIPPING AND AMPLITUDE CORRECTION ?