Mutations in the catalytic subunit of the cAMP-dependent protein kinase interfere with holoenzyme formation without disrupting inhibition by protein kinase inhibitor

摘要: Three amino acids were identified in the catalytic (C) subunit of cyclic AMP-dependent protein kinase that are involved interaction with regulatory (R) subunit, but not specific inhibitor, PKI. In a functional assay for gene induction, C expression vector serine or arginine substituted Leu-198 and double mutant C, His-87-->Gln/Trp-196-->Arg (Orellana, S. A., McKnight, G. (1992) Proc. Natl. Acad. Sci, U.S.A. 89, 4726-4730), retained activity presence an excess RI RII. contrast, cotransfection full-length PKI completely inhibited both wild type subunits. These data suggest although substrate/pseudosubstrate sites R interact at site, there is additional domain on holoenzyme formation distinct from specifying high affinity binding.