This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
1bw5
From Proteopedia
THE NMR SOLUTION STRUCTURE OF THE HOMEODOMAIN OF THE RAT INSULIN GENE ENHANCER PROTEIN ISL-1, 50 STRUCTURES
Overview
Homeodomains are one of the key families of eukaryotic DNA-binding motifs and provide an important model system for DNA recognition. We have determined a high-quality nuclear magnetic resonance (NMR) structure of the DNA-binding homeodomain of the insulin gene enhancer protein Isl-1 (Isl-1-HD). It forms the first solution structure of a homeodomain from the LIM family. It contains a well-defined inner core (residues 12-55) consisting of the classical three-helix structure observed in other homeodomains. The N terminus is unstructured up to residue 8, while the C terminus gradually becomes unstructured from residue 55 onwards. Some flexibility is evident in the loop parts of the inner core. Isl-1-HD has, despite its low sequence identity (23-34 %), a structure that is strikingly similar to that of the other homeodomains with known three-dimensional structures. Detailed analysis of Isl-1-HD and the other homeodomains rationalizes the differences in their temperature stability and explains the low stability of the Isl-1-HD in the free state (tm 22-30 degrees C). Upon DNA binding, a significant stabilization occurs (tm>55 degrees C). The low stability of Isl-1-HD (and other mammalian homeodomains) suggests that in vivo Isl-1-HD recognizes its cognate DNA from its unfolded state.
About this Structure
1BW5 is a Single protein structure of sequence from Rattus norvegicus. Full crystallographic information is available from OCA.
Reference
The solution structure of the homeodomain of the rat insulin-gene enhancer protein isl-1. Comparison with other homeodomains., Ippel H, Larsson G, Behravan G, Zdunek J, Lundqvist M, Schleucher J, Lycksell PO, Wijmenga S, J Mol Biol. 1999 May 14;288(4):689-703. PMID:10329173 Page seeded by OCA on Fri May 2 12:01:31 2008
