Kinase Family PKA

Kinase Classification: Group AGC: Family PKA

The PKA family has two putative subfamlies: PKA, and PRKX.

PRKA

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.

PRKX

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.

PRKY details

Human PRKY has lost the 6th coding exon from the genome, and 10 ESTs and cDNAs confirm that the transcript splices from exon 5 to exon 7, resulting in a frameshift and premature stop to the ORF. This change removes the last 31 AA of the kinase domain and the PKC-Cterminal domain. The chimp retains exon 6 and appears to encode a full length gene. No other homologs have been found in cDNA/EST databases, whole genome shotgun datasets or in assembled genomes, though Y chromosomes are frequently not sequenced or undersequenced (if the samples are not all male) or are poorly assembled due to their highly repetitive nature. Comparison of the chimp and human ORFs upstream of the deleted exon, with PRKX from several primates, suggests that PRKY is not under purifying selection in human, and may even be under positive selection in chimp, though the numbers are very low.

--Gerard 13:48, 27 May 2010 (PDT)