1EQ8

THREE-DIMENSIONAL STRUCTURE OF THE PENTAMERIC HELICAL BUNDLE OF THE ACETYLCHOLINE RECEPTOR M2 TRANSMEMBRANE SEGMENT

SOLID-STATE NMR

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NMR Experiment
Experiment	Type	Sample Contents	Solvent	Ionic Strength	pH	Pressure	Temperature (K)	Spectrometer
1	HSQC; HNCA; HNCOCA; 3D 15N- and 13C-edited NOESY; 3D 15N- and 13C-edited TOCSY; 3D HNHA	1mM M2 U-15N; 350mM DPC; pH5.5;	90% H2O/10% D2O		5.5	ambient	303
2	1D CPMOIST; 2D 1H/1H-15N PISEMA; 2D 1H/15N HETCOR;	20mg M2 U-15N; 40mg DMPC;	DMPC bilayers in H2O;		5.5	ambient	298

NMR Spectrometer Information
Spectrometer	Manufacturer	Model	Field Strength
1	Bruker	DMX	750
2	Bruker	DMX	600
3	Chemagnetics	CMX	400

NMR Refinement
Method	Details	Software
X-PLOR 3.1, distance geometry, simulated annealing, molecular dynamics, FISI, FINGERPRINT, HOLE	The backbone coordinates obtained from solution NMR were superimposed on the coordinates obtained from solid-state NMR to fix the helix orientation and rotation in the membrane. The pentameric array was then optimized using molecular dynamics. Pore contours were calculated with the program HOLE.	X-PLOR

NMR Ensemble Information
Conformer Selection Criteria	structures with favorable non-bond energy
Conformers Calculated Total Number	30
Conformers Submitted Total Number	1
Representative Model	(minimized average structure)

Additional NMR Experimental Information
Details	The orientation of each monomer in the pentameric bundle was obtained from the combination of the solution NMR (PDB file 1a11) and solid-state NMR (PDB file 1cek) structures

Computation: NMR Software
#	Classification	Version	Software Name	Author
1	refinement	X-PLOR	3.01	Brunger
2	structure solution	FISI	1.01	Marassi
3	structure solution	HOLE		Smart, Goodfellow, Wallace
4	data analysis	Felix	95