Structures of cGMP-Dependent Protein Kinase (PKG) Iα Leucine Zippers Reveal an Interchain Disulfide Bond Important for Dimer Stability.

cGMP-dependent protein kinase (PKG) Iα is a central regulator of smooth muscle tone and vasorelaxation. The N-terminal leucine zipper (LZ) domain dimerizes and targets PKG Iα by interacting with G-kinase-anchoring proteins. The PKG Iα LZ contains C42 that is known to form a disulfide bond upon oxidation and to activate PKG Iα.

Crystal structure of the cGMP-dependent protein kinase II leucine zipper and Rab11b protein complex reveals molecular details of G-kinase-specific interactions.

cGMP-dependent protein kinase (PKG)-interacting proteins (GKIPs) mediate cellular targeting of PKG isoforms by interacting with their leucine zipper (LZ) domains. These interactions prevent aberrant signaling cross-talk between different PKG isotypes. To gain detailed insight into isotype-specific GKIP recognition by PKG, we analyzed the type II PKG leucine zipper domain and found that residues 40-83 dimerized and specifically interacted with Rab11b.