A dual-specificity isoform of the protein kinase inhibitor PKI produced by alternate gene splicing.
We have previously shown that the protein kinase inhibitor beta (PKIbeta) form of the cAMP-dependent protein kinase inhibitor exists in multiple isoforms, some of which are specific inhibitors of the cAMP-dependent protein kinase, whereas others also inhibit the cGMP-dependent enzyme [Kumar, Van Patten and Walsh (1997), J. Biol. Chem. 272, 20011-20020]. We have now demonstrated that the switch from a cAMP-dependent protein kinase (PKA)-specific inhibitor to one with dual specificity arises as a consequence of alternate gene splicing. We have confirmed using bacterially produced pure protein that a single inhibitor species has dual specificity for both PKA and cGMP-dependent protein kinase (PKG), inhibiting each with very high and closely similar inhibitory potencies. The gene splicing converted a protein with 70 amino acids into one of 109 amino acids, and did not change the inhibitory potency to PKA, but changed it from a protein that had no detectable PKG inhibitory activity to one that now inhibited PKG in the nanomolar range.
Kumar
Priyadarsini
P
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, U.S.A.
Walsh
Donal A
DA
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D003001:Cloning, Molecular; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors*; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000235:genetics; D013379:Substrate Specificity
D002352:Carrier Proteins; D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; C107591:PKIB protein, human; D020033:Protein Isoforms; D017868:Cyclic AMP-Dependent Protein Kinases; D017869:Cyclic GMP-Dependent Protein Kinases