REAGENT or RESOURCE	SOURCE	IDENTIFIER
Antibodies
Polyclonal anti human MUC2-D3	This study	N/A
Polyclonal anti mouse Muc2-D3	This study	N/A
Goat anti rabbit HRP	Jackson ImmunoResearch	Cat# 111-035-003; RRID: AB_2313567
Bacterial and Virus Strains
E. coli XL-1 blue	Agilent	Cat# 200249
Biological Samples
Murine colon lumen extracts	This study	N/A
Chemicals, Peptides, and Recombinant Proteins
Tobacco Etch Virus protease	Produced in-house	N/A
Secreted protease of C1 esterase inhibitor (StcE)	Expression plasmid provided by Carolyn Bertozzi; Malaker et al., 2019	N/A
	Protein produced in-house
PEI MAX reagent	Polysciences	Cat# 24765-1
Deposited Data
One-bead cryo-EM map	This study	EMDB: 10517
Two-bead cryo-EM map	This study	EMDB: 11658
MUC2 D1D2D3CysD1 atomic coordinates	This study	PDB: 6TM2
Atomic coordinates for three beads of the MUC2 head filament	This study	PDB: 7A5O
CysD1 atomic coordinates	This study	PDB: 6TM6
MUC2 D3 dimer atomic coordinates	Javitt et al., 2019	PDB: 65BF
VWF D'D3 module atomic coordinates	Dong et al., 2019	PDB: 6N29
Experimental Models: Cell Lines
FreeStyle 293-F Cells	Thermo Fisher Scientific	Cat# R79007
Experimental Models: Organisms/Strains
C57Bl mice	Bred in house	N/A
Recombinant DNA
MUC2 D1D2D3CysD1 expression plasmid	Javitt et al., 2019	Addgene ID: 155214
MUC2 D1D2D3 expression plasmid	Javitt et al., 2019	Addgene ID: 155215
MUC2 D3 expression plasmid	Javitt et al., 2019	Addgene ID: 155216
MUC2 CysD1 expression plasmid	This study	N/A
MUC2 D1D2D3CysD1 C1088A expression plasmid	This study	N/A
MUC2 D1D2D3CysD1 C1130A expression plasmid	This study	N/A
MUC2 D1D2D3CysD1 C1088A/C1130A expression plasmid	This study	N/A
Muc5b D1D2D3CysD1 expression plasmid	This study	N/A
Software and Algorithms
SerialEM	Mastronarde, 2005	https://bio3d.colorado.edu/SerialEM/
Pymol	DeLano, 2002	https://pymol.org/2/
Coot	Emsley et al., 2010	https://www2.mrc-lmb.cam.ac.uk/personal/pemsley/coot/
CryoSPARC	Punjani et al., 2017	https://cryosparc.com/
Chimera	Pettersen et al., 2004	https://www.cgl.ucsf.edu/chimera/
Phenix	Adams et al., 2010	https://www.phenix-online.org/
Modeller	Webb and Sali, 2016	https://salilab.org/modeller/
SHELX	Sheldrick, 2015	https://ccp4serv7.rcharwell.ac.uk/ccp4online/
Molprobity	Chen et al., 2010	http://molprobity.biochem.duke.edu/
SMOG2	Noel et al., 2016	http://smog-server.org/smog2/
GROMACS	Pronk et al., 2013	http://www.gromacs.org/
Dynamics	Wyatt Technology	https://www.wyatt.com/products/software/dynamics.html
MetaMorpheus	Solntsev et al., 2018	https://github.com/smith-chem-wisc/MetaMorpheus
Other
Formvar/carbon 300 mesh copper grids	Electron Microscopy Sciences	Cat# FCF300-Cu
Quantifoil R1/2 300 mesh copper grids	Quantifoil	Cat# Q3100CR-12