Identification and characterization of novel mutations in the human gene encoding the catalytic subunit Calpha of protein kinase A (PKA).

ABSTRACT: The genes PRKACA and PRKACB encode the principal catalytic (C) subunits of protein kinase A (PKA) C? and C?, respectively. C? is expressed in all eukaryotic tissues examined and studies of C? knockout mice demonstrate a crucial role for C? in normal physiology. We have sequenced exon 2 through 10 of PRKACA from the genome of 498 Norwegian donors and extracted information about PRKACA mutations from public databases. We identified four interesting nonsynonymous point mutations, Arg45Gln, Ser109Pro, Gly186Val, and Ser263Cys, in the C?1 splice variant of the kinase. C? variants harboring the different amino acid mutations were analyzed for kinase activity and regulatory (R) subunit binding. Whereas mutation of residues 45 and 263 did not alter catalytic activity or R subunit binding, mutation of Ser(109) significantly reduced kinase activity while R subunit binding was unaltered. Mutation of C? Gly(186) completely abrogated kinase activity and PKA type I but not type II holoenzyme formation. Gly(186) is located in the highly conserved DFG motif of C? and mutation of this residue to Val was predicted to result in loss of binding of ATP and Mg(2+), which may explain the kinetic inactivity. We hypothesize that individuals born with mutations of Ser(109) or Gly(186) may be faced with abnormal development and possibly severe disease.

SUBMITTER: Soberg K 

PROVIDER: S-EPMC3325940 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature