TABLE 1.

The ΔG_app (kcal mol⁻¹) of the TM domain of the Pf3-aTM constructs

The TM domain hydrophobicity ΔG_app (kcal mol⁻¹) of Pf3-aTM constructs were calculated using the D23A mutant as a basis (ΔG_app of *D23A mutant = −1.17). ΔG_app is the computed free energy of a TM segment from a Sec61 translocon to a dog pancreas microsomal membrane as described (44, 55) (reviewed in Ref. 19). The free energy values of individual amino acids depend upon their positions in the TM helix. Arg, Lys, Asp, and Glu are strongly position-dependent; they affect insertion marginally near helix ends but have a big effect near helix centers. The position dependence is apparent in the values listed (e.g. compare F35D and F39D). The values in the table were computed with the totalizer module of MPEx (51) using the translocon hydrophobicity values (44).

Asp mutants	ΔGapp	Arg mutants	ΔGapp	Lys mutants	ΔGapp	Asn mutants	ΔGapp
T19D	−0.87	T19R	−1.17
D23Ia	−1.42	D23R	−0.93	D23K	−0.46	D23N	−0.43
F27D	+0.81	F27R	+0.48	F27K	+0.84	F27N	+0.37
L31D	+1.28	L31R	+0.91			L31N	+0.79
F35D	+0.52	F35R	−0.36			F35N	+0.42
F39D	−0.29

^a Insertion independent of YidC. All other TM segments require YidC.