Kinase Family PKA
Protein Kinase A (PKA) is a cAMP-dependent protein kinase with many cellular functions. It is activated by cAMP binding to its regulatory subunit, which then activates the catalytic subunit. In basal organisms, these two subunits may be fused.
The PKA family has the following subfamilies
Protein Kinase A is the best known structural and mechanistic model for the ePK superfamily. Three members are found in human, and the gene is found in most eukaryotes. It is activated by cyclic AMP and mediates a wide number of signaling functions.
In human, this consists of PRKX, on the X chromosome, and PRKY, a possible pseudogene found on the Y chromosome. Preliminary analysis indicates that distinct PRKX genes (as opposed to PKA family genes) are found in both Drosophila and C. elegans.
This subfamily is found in land plants, at least one alga and stramenopiles (oomycetes). It consists of a PP2C phosphatase domain followed by a pair of cNMP-binding domains that are most similar to those of the PKA catalytic subunit, followed by a kinase domain that is most similar to the PKA catalytic subunit, but which has multiple changes that suggest it is a pseudokinase. These proteins are often annotated as PKG since they contain both cNMP-binding and kinase domains in the one polypeptide, and PKG proteins are typically their best blast hits.
Other Basal PKA
Several basal eukaryotic lineages have kinases that contain both cNMP-binding and kinase domains, with the domains most similar to those of animal PKA, but the domain arrangement similar to that of PKG. These have not yet been placed in defined subfamilies.
Gerard 00:26, 8 March 2012 (UTC)