Comparison of hetero-two-stranded coiled-coil with homo-two-stranded coiled-coil neck regions. Panel A depicts the CD spectra of the three heptad coiled-coils for the neck regions of Kif3A/Kif3B, Kif3A, and Kif3B (peptides P2/P7, P2 and P7, respectively). Panel B depicts the relative stabilities of the neck region coiled-coils in guanidine hydrochloride. Panel C depicts the relative stabilities of the neck region coiled-coils for the homo-and hetero-two-stranded peptides in urea. Homostranded Kif3A neck region, P2, (open circles); homostranded Kif3B neck region, P7, (open squares); heterostranded Kif3A/ Kif3B neck region, P2/P7, (closed triangles). Peptide sequences are shown in Fig. 3.