Tom Sandbox: Difference between revisions

GCN4 (PDB [[2zta]] by itself, [[1ysa]] bound to DNA) is a eukaryotic transcription factor first isolated from Saccharomyces cerevisiae, also known as Baker's Yeast. The first 'leucine zipper' model was coined by Landshulz et al. in 1988. Today, while the name has stayed the same, we no longer view the leucine binding region in an inter-collated manner, but as leucines meeting face to face <ref name="abc"> Oas, T. G.;  McIntosh, L. P.;  O'Shea, E. K.;  Dahlquist, F. W.; and  Kim, P. S. Biochemistry 1990 29 (12), 2891-2894 </ref>. (see heptad repeat section)

At every d and d' we have a Leucine, while at the a and a' locations we typically see valine. <ref name="Voet" /> In the opposite positions one tends to see more charged and polar residues. The Leucine and Valine repeats create a strongly hydrophobic region between the two alpha helices. This clearly shows the relationship between coils and shown below, we can see that for the two helices to be symmetrical, the Leucines must not in fact be oriented as a zipper, but on the same levels.