ELECTRON MICROSCOPY

Sample

Mouse leptin in complex with a trimerized form of the mouse Lep-R extracellular region

Specimen Preperation
Sample Aggregation State PARTICLE
Vitrification Instrument LEICA EM GP
Cryogen Name ETHANE
Sample Vitrification Details ?
3D Reconstruction
Reconstruction Method SINGLE PARTICLE
Number of Particles 163914
Reported Resolution (Å) 4.02
Resolution Method FSC 0.143 CUT-OFF
Other Details To address the breakage of symmetry in the ring-like core region of the complex and possibly revolve the mLEP-RCRH2:mLeptin:mLEP-RCRH1-IgCRH2 subcomplex at higher resolution, the pseudo-C3 symmetric volume following consenus refinement was aligned to the pseudo-C3 symmetry axis via the Volume Alignment Tool job in cryoSPARC. The associated particle set was re-extracted without binning and symmetry expanded around the C3 axis resulting in 163,914 particles. Using the molmap function in Chimera, a volume blurred to 25 Angstrom around one mLEP-RCRH2:mLeptin:mLEP-RCRH1-IgCRH2 subcomplex was generated, and transformed into a mask with the Volume Tools job in cryoSPARC. Local refinement was performed by limiting the rotation and shift search extent around the original consensus refinement. The center of mass of the mask was used as a fulcrum point. This approach resulted in a cryo-EM map with an FSC0.143 resolution of 4.02 Angstrom in which the crystallographic model for the mLEP-RCRH2:mLeptin:mLEP-R_IgCRH2' complex was fitted using Chimera and real-space refined in Phenix using reference restraints to the starting model.
Refinement Type
Symmetry Type POINT
Map-Model Fitting and Refinement
ID 1
Refinement Space REAL
Refinement Protocol FLEXIBLE FIT
Refinement Target ?
Overall B Value ?
Fitting Procedure ?
Details The crystallographic model for the mLEP-RCRH2:mLeptin:mLEP-R_IgCRH2' complex (pdb 7z3r) was fitted in the cryo-EM map using Chimera and real-space refined in Phenix using reference restraints to the starting model.
Data Acquisition
Detector Type GATAN K3 BIOQUANTUM (6k x 4k)
Electron Dose (electrons/Å2) 45
Imaging Experiment
Date of Experiment ?
Temprature (Kelvin)
Microscope Model TFS KRIOS
Minimum Defocus (nm) 1200
Maximum Defocus (nm) 2500
Minimum Tilt Angle (degrees) ?
Maximum Tilt Angle (degrees) ?
Nominal CS 2.7
Imaging Mode OTHER
Specimen Holder Model ?
Nominal Magnification 105000
Calibrated Magnification ?
Source FIELD EMISSION GUN
Acceleration Voltage (kV) 300
Imaging Details ?
Imaging Experiment
Task Software Package Version
CTF CORRECTION cryoSPARC v3.3.1
MODEL FITTING UCSF Chimera 1.17
MODEL REFINEMENT PHENIX 1.19.2-4158
INITIAL EULER ASSIGNMENT cryoSPARC v3.3.1
CLASSIFICATION cryoSPARC v3.3.1
RECONSTRUCTION cryoSPARC version 3.3.2
Image Processing
CTF Correction Type CTF Correction Details Number of Particles Selected Particle Selection Details
PHASE FLIPPING AND AMPLITUDE CORRECTION ?