Table 1.

M₂ TM bundle parameters obtained from PI(n), hydrophobicity (Hb) (28), and positional propensity (P) (21) analysis

Parameter	C, residues	D, residues	Pitch angle,* α	Pairwise helix crossing angle,† ɛ
PI(n)	2.58  ±  0.91	3.46  ±  0.09	−14.5  ±  9.2	19.4
Hb	2.44  ±  0.82	3.45  ±  0.08	−15.5  ±  8.2	20.5
P	2.65  ±  0.95	3.48  ±  0.10	−12.4  ±  10.3	16.8
Average	2.56  ±  0.51	3.46  ±  0.05	−14.1  ±  5.3	18.9

^*α can be predicted from the sequence-defined period (D), the repeat of the α-helix (a), the effective radius of the α-helix (r⁰), and the helical rise per residue (h) (22, 29) as in Eq. 3 of the text, where r⁰ = 5.5 Å, h = 1.5 Å, and a = 3.60. The errors reflect the uncertainty in α based on the uncertainty in D and a (30).

^†Calculated using equation 11 of ref. 22.