TABLE 1.

Count of the native contacts in the α-helical domains (H1 and H2) in the N terminus, C terminus, and internal repeats of NI6C

Domain	Sequencea	No. of residues	No. of all contactsb	No. of inter-repeat contactsb
N-terminal	Asp7–Gln30	24	85	49
C-terminal	Thr241–Gln259	19	70	45
Internal	Thr109–Ala129	21	129	101

^a NI6C was built using the x-ray structure of NI3C (Protein Data Bank code 2QYJ); the residues were renumbered (see details in supplemental Fig. S4).

^b The differences in the numbers of native and inter-repeat contacts lead to significant differences in stability between the repeats, as indicated by the energy function.