Introduction - This script shows the changes in structure of the Arc
repressor after mutating the amino acid sequence of the β-sheet.
(Based on MH Cordes et al. Science 284 325 (1999)).
This is the native Arc repressor. Note the β-sheet. See how
Leu 12 points to the interior of the protein and
Asn 11 points outward.
Residues 11 and 12 have changed ordder in this "switch" mutant. But, see how
Leu (now 11) points to the interior of the protein
and Asn (now 12) points outward; the
β-sheet has been converted to a short α-helix.