Table 1.

Secondary structure fractions of 13 membrane proteins obtained from crystal structures

Membrane protein	PBD code	Resolution (Å)	αR	αD	βR	βD	T	U
Reaction center (R. viridis)	1prc	2.30	0.291	0.186	0.024	0.042	0.194	0.263
Photosystem I	1jb0	2.50	0.363	0.193	0.025	0.029	0.167	0.222
Reaction center (R. sphaeroides)	1qov	2.10	0.341	0.185	0.035	0.035	0.138	0.263
Antenna complex (R. acidophila)	1nkz	2.00	0.569	0.161	0.000	0.000	0.086	0.183
Ubiquinol-cytochrome c reductase (bovine)	1bgy	3.00	0.355	0.163	0.056	0.034	0.165	0.228
Cytochrome oxidase (bovine)	1occ	2.80	0.434	0.146	0.031	0.022	0.141	0.226
Rhodopsin (bovine)	1f88	2.80	0.482	0.153	0.012	0.025	0.160	0.166
Bacteriorhodopsin (H. halobium)	1qhj	1.90	0.605	0.154	0.035	0.017	0.109	0.079
Ca2+ ATPase (rabbit muscle)	1eu1	2.60	0.286	0.154	0.087	0.058	0.203	0.211
Porin (OmpF, E. coli)	2omf	2.40	0.010	0.035	0.462	0.118	0.223	0.153
Porin (R. capsulatus)	2por	1.80	0.027	0.040	0.462	0.106	0.193	0.172
Maltoporin (LamB)	1af6	2.40	0.000	0.028	0.482	0.114	0.159	0.216
Phosphoporin (PhoE)	1pho	3.00	0.000	0.020	0.433	0.115	0.236	0.194

The assignments of secondary structure are from the DSSP method (Kabsch and Sander 1983). The secondary structure fractions are regular α-helix (α_R), distorted α-helix (α_D), regular β-sheet (β_R), distorted β-sheet (β_D), turns (T), and unordered (U), as defined by Sreerama et al. (1999). The references for the crystal structures are provided in Electronic Supplemental Material (Table S1).