8UXX

Arp2/3 branch junction complex, BeFx state

ELECTRON MICROSCOPY

Sample
Arp2/3 branch complex (ADP-BeFx state)
Sample Components
Arp2/3 complex
Actin

Specimen Preparation
Sample Aggregation State	PARTICLE
Vitrification Instrument	FEI VITROBOT MARK IV
Cryogen Name	ETHANE
Sample Vitrification Details	The samples were incubated on the grid for 50 s and the extra solution was blotted using two Vitrobot filter papers (0.55/20 mm, Grade 595, Ted Pella) ...	The samples were incubated on the grid for 50 s and the extra solution was blotted using two Vitrobot filter papers (0.55/20 mm, Grade 595, Ted Pella) for 4 s at 0 blot force. The grids were plunged into liquid ethane at ~180 degrees C with a wait time of 0.5 s.

3D Reconstruction
Reconstruction Method	SINGLE PARTICLE
Number of Particles	200000
Reported Resolution (Å)	3.2
Resolution Method	FSC 0.143 CUT-OFF
Other Details
Refinement Type
Symmetry Type	POINT

Map-Model Fitting and Refinement
Id	1
Refinement Space
Refinement Protocol
Refinement Target
Overall B Value
Fitting Procedure
Details

Data Acquisition
Detector Type	GATAN K3 (6k x 4k)
Electron Dose (electrons/Å**2)	51.4

Imaging Experiment	1
Date of Experiment
Temperature (Kelvin)
Microscope Model	FEI TITAN KRIOS
Minimum Defocus (nm)	1200
Maximum Defocus (nm)	2500
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	64000
Calibrated Magnification
Source	FIELD EMISSION GUN
Acceleration Voltage (kV)	300
Imaging Details	The vitrified grids were screened for sample homogeneity and ice thickness in a Glacios 200 kV transmission electron microscope equipped with Gatan K2 summit camera. Electron micrographs for image reconstructions were collected using Titan Krios equipped with X-cold field emission gun at 300 kV, Gatan image filter with slit width of 20 eV and a nanoprobe.

EM Software
Task	Software Package	Version
IMAGE ACQUISITION	SerialEM
FINAL EULER ASSIGNMENT	cryoSPARC	3.0
CLASSIFICATION	cryoSPARC	3.0
RECONSTRUCTION	cryoSPARC	3.0

Image Processing
CTF Correction Type	CTF Correction Details	Number of Particles Selected	Particle Selection Details
PHASE FLIPPING AND AMPLITUDE CORRECTION		3000000

RCSB PDB Core Operations are funded by the U.S. National Science Foundation (DBI-2321666), the US Department of Energy (DE-SC0019749), and the National Cancer Institute, National Institute of Allergy and Infectious Diseases, and National Institute of General Medical Sciences of the National Institutes of Health under grant R01GM133198.