THE A-KINASE ANCHORING DOMAIN OF TYPE II-ALPHA CAMP-DEPENDENT PROTEIN-KINASE IS HIGHLY HELICAL

Subcellular localization of the type II cAMP-dependent protein kinase is controlled by interaction of the regulatory subunit with A-Kinase A nchoring Proteins (AKAPs). This contribution examines the solution str ucture of a 44-residue region that is sufficient for high affinity bin ding to AKAPs. The N-terminal dimerization domain of the type II alpha regulatory subunit of cAMP-dependent protein kinase was expressed to high levels on minimal media and uniformly isotopically enriched with N-15 and C-13 nuclei. Sequence-specific backbone and side chain resona nce assignments have been made for greater than 95% of the amino acids in the free dimerization domain using high resolution multidimensiona l heteronuclear NMR techniques. Contrary to the results from secondary structure prediction algorithms, our analysis indicates that the doma in is :highly helical with a single 3-5-residue sequence involved in a beta-strand. The assignments and secondary structure analysis provide the basis for analyzing the structure and dynamics of the dimerizatio n domain both free and complexed with specific anchoring proteins.