Subdomain VII of Kinase Domain of Protein Kinase A

Subdomain VII has a beta strand- loop- beta strand structure. The strands are beta strands 8 and 9. This subdomain contains a very well conserved triplet of Asp-Phe-Gly, occupying positions 184-186. The triplet lies in the first loop, which is stabilized by a hydrogen bond between Asp184 and Gly186. Asp184 is an invariant residue having the function of orienting the gamma phosphate of MgATP for transfer to the substrate. It does this by chelating the primary activiating Mg2+ions that bridge the beta and gamma phosphates of the ATP. (The entire subdomain is fairly well conserved, but in some cases, for example Cdk2, the second beta strand in this subdomain is replaced with an alpha helix)