The First Crystal Structure of cyclic GMP-dependent protein kinase Iβ dimerization domain reveals the molecular features of an extended leucine/isoleucine zipper

From Q-bio

Targeting of cGMP-dependent protein kinase (PKG) provides a mechanism for substrate specificity and is mediated by the dimerization/docking (D/D) domain. Although D/D of PKG Iβ has been shown to binds to TFII-I and IRAG, the structural detail was unknown. To understand its targeting mechanism, we solved crystal structures of PKG Iβ D/D. The structure reveals two helices warping around into a left-handed helix forming a novel leucine zipper. Surprisingly, it also shows positive residues at the d positions forming interhelical interactions with negative residues at the e positions. These interactions flank the docking surface and thus may stabilize the surface.