Table II. Intersubunit interfaces^a.

Interface	Area in interface (Å2)	Interface surface area of each subunitb (%)	Positions involved in the main interactions (%)	Hydrophobicityc (%)
A/B	846	14.0	a, d/a, d (81.3)	83.2
C/D	842	13.7	a, d/a, d (83.4)	84.7
B/C	820	13.3	b, e/c, g (73.7)	62.4
A/D_symm1d	730	12.0	b, e/c, g (72.9)	63.4
A/C_symm1e	747	12.4	c, g/b, e (73.2)	65.0
B/D_symm2f	447	7.3	c, d, g/a, b, e, fg	65.0

^aAll the helices were reduced to the size of the shortest one (residues 23–78).

^bRelative to total surface area.

^cSurface area involving carbon atoms is considered to be hydrophobic.

^dThe crystallographic symmetry operator for a D_symm1 molecule is a translation of one unit cell in x, y and z.

^eThe crystallographic symmetry operator for a C_symm1 molecule is 2 – x, y + 1/2, 1 – z.

^fThe crystallographic symmetry operator for a D_symm2 molecule is –x, y + 1/2, –z.

^gThe positions involved in the main interactions between these two helices do not follow a regular pattern.