Seven mutations in the human insulin gene linked to permanent neonatal/infancy-onset diabetes mellitus
J. Clin. Invest. Carlo Colombo, et al. 118:2148 doi:10.1172/JCI33777 [
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Figure 3Secondary structure computer modeling of WT and mutant proinsulins. Shown are superimposed Cα traces of WT (blue) and all mutated insulins (purple), with the exception of L
B6V. The positions of disulfide bridges are also marked. None of the mutations caused substantial distortion of the secondary structure, with the exception of L
B15Y
B16delinsH (yellow trace at left), where an α-helical disruption is apparent (arrow). This was also evident in the superimposition of WT insulin and L
B15Y
B16delinsH. The L
B6P mutation alters the hydrophobic core of the protein. The L
B11P mutation affects the hydrophobic core of the protein. The C
A6Y mutation disrupts the A6–A11 disulfide bridge; the tyrosine is oriented inside the hydrophobic core of the protein, where it engages L
B6 in a stacking interaction. The
hAkita mutation — used in this study as positive control — disrupts the B7–A7 disulfide bridge, and the tyrosine is solvent exposed.