TABLE 1.

Minimum energy orientations for membrane proteins of known conformation

Calculated minimum energy orientation
PDB	Protein	Organism	Tilt angle (°)	z (Å)	ΔE (kcal/mol)
1afo	Glycophorin A	Human red blood cell	14	3.7	−70.7
1cwq	Bacteriorhodopsin	Halobacterium salinarium	30	1	−29.9
1h68	Sensory rhodopsin II	Natronomonas pharaonis	3	0.7	−86.6
1j4n	Aquaporin	Bovine red blood cell	14	0.3	−83.2
1rc2	Aquaporin	Escherichia coli	8	0.7	−108.1
1kpk	Chloride channel homologue	E. coli	3	3	−90.5
1kpl	Chloride channel homologue	Salmonella typhimurium	3	3.1	−82.6
1cx2	Cyclooxygenase-2	Mouse	0	36	−95.3

The protein tilt angle, displacement of the center of mass with respect to the membrane center (z), and insertion energy (ΔE) are listed for all systems. The membrane center is located at z = 0 and negative z values correspond to shifts toward the extracellular side, whereas positive z values correspond to shifts toward the cytoplasm. For 1afo, 1j4n, 1rc2, 1kpk, 1kpl, and 1cx2, the tilt angle is given with respect to the multimer.