8AVO | pdb_00008avo

Human leptin in complex with the human LEP-R ectodomain fused to a C-terminal trimeric isoleucine GCN4 zipper (open 3:3 model).

ELECTRON MICROSCOPY

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Starting Model(s)

Initial Refinement Model(s)
Type	Source	Accession Code	Details
experimental model	PDB	7Z3R
experimental model	PDB	7Z3Q

Refinement

RMS Deviations
Key	Refinement Restraint Deviation
f_dihedral_angle_d	11.0077
f_angle_d	0.6459
f_chiral_restr	0.0467
f_plane_restr	0.0064
f_bond_d	0.0024

Sample
Human leptin in complex with the human LEP-R ectodomain C-terminally fused to a trimeric GCN4 isoleucine zipper tag

Specimen Preparation
Sample Aggregation State	PARTICLE
Vitrification Instrument	FEI VITROBOT MARK IV
Cryogen Name	ETHANE
Sample Vitrification Details

3D Reconstruction
Reconstruction Method	SINGLE PARTICLE
Number of Particles	30353
Reported Resolution (Å)	6.84
Resolution Method	FSC 0.143 CUT-OFF
Other Details
Refinement Type
Symmetry Type	POINT
Point Symmetry	C1

Map-Model Fitting and Refinement
Id	1 (7Z3R, 7Z3Q)
Refinement Space	REAL
Refinement Protocol	FLEXIBLE FIT
Refinement Target
Overall B Value
Fitting Procedure
Details	Atomic models for the 2:2 and 3:3 hLeptin:hLEP-R complexes were created based on the Alphafold2 predictions for hLEP-R and hLeptin, and the crystal structures for the mouse 3:3 Leptin:LEP-RIgCRH2 complex (pdb 7z3r) and the human Leptin:LEP-RCRH2 complex (pdb 7z3q) and fitted in the cryo-EM maps via Chimera. Atomic models were further refined via real space refinement in Phenix using rigid body refinement and coordinate refinement with reference restraints to the starting model.

Data Acquisition
Detector Type	GATAN K3 (6k x 4k)
Electron Dose (electrons/Å**2)	62.4

Imaging Experiment	1
Date of Experiment
Temperature (Kelvin)
Microscope Model	JEOL CRYO ARM 300
Minimum Defocus (nm)	800
Maximum Defocus (nm)	3000
Minimum Tilt Angle (degrees)
Maximum Tilt Angle (degrees)
Nominal CS
Imaging Mode	OTHER
Specimen Holder Model
Nominal Magnification
Calibrated Magnification
Source	FIELD EMISSION GUN
Acceleration Voltage (kV)	300
Imaging Details

EM Software
Task	Software Package	Version
PARTICLE SELECTION	cryoSPARC	v3.1.0
CTF CORRECTION	cryoSPARC	v3.1.0
MODEL FITTING	UCSF Chimera	1.17
MODEL REFINEMENT	PHENIX	1.19.2
INITIAL EULER ASSIGNMENT	cryoSPARC	v3.1.0
CLASSIFICATION	cryoSPARC	v3.1.0
CLASSIFICATION	cryoSPARC	v3.1.0
RECONSTRUCTION	cryoSPARC	v3.3.2

Image Processing
CTF Correction Type	CTF Correction Details	Number of Particles Selected	Particle Selection Details
PHASE FLIPPING AND AMPLITUDE CORRECTION		206218	Initial 2D-classes were obtained via template-based particle picking using 2D-classes for a mLeptin:mLEP-R-deltaFnIII-tGCN4 complex lowpass filtered to 20 Angstrom. These 2D classes were then used to seed template-based picking and neural network-based particle picking via Topaz 0.2.4. Junk particles were removed by multiple rounds of 2D classification resulting in a particle set of 206,218 particles. High-resolution 2D classes were selected for ab initio 3D classification followed by heterogeneous refinement and non-uniform refinement.