1H, 13C and 15N assignment of the Isl-1 homeodomain.

Abstract

Key words: Isl-1, homeodomain, protein, DNA-binding, NMR assignmentBiological contextTheinsulin geneenhancerbindingprotein, Isl-1, bindsspecifically to a transcription activation domain of theinsulin gene in rat (Karlsson et al., 1990), acts asa positive regulator of the proglucagon genes (Wangand Drucker, 1995), and is required for embryonicneuron differentiation (Pfaff et al., 1996). Isl-1 has amolecular weight of 42 kDa, and contains two aminoterminal zinc-binding LIM domains (Karlsson et al.,1990; McGurie et al., 1992), and a C-terminal regionrelated to homeodomains in other DNA binding pro-teins. The homeodomain region of Isl-1, Isl-1-HD (66amino acids), mediates its DNA binding through se-quencespecific recognitionof duplexDNA containinga –TAAT– sequence (Behravan et al., 1997). We havenow used NMR to determine the solution structure ofthe Isl-1-HD (Ippel et al., to be published), while stud-ies on the Isl-1-HD/DNA complexare still in progress.Here we report the assignment of the