R-subunit Isoform Specificity in Protein Kinase A: Distinct Features of Protein Interfaces in PKA Types I and II by Amide H/2H Exchange Mass Spectrometry

Ganesh S. Anand, Matthew Hotchko, Simon H.J. Brown, Lynn F. Ten Eyck, Elizabeth A. Komives, Susan S. Taylor

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

The two isoforms (RI and RII) of the regulatory (R) subunit of cAMP-dependent protein kinase or protein kinase A (PKA) are similar in sequence yet have different biochemical properties and physiological functions. To further understand the molecular basis for R-isoform-specificity, the interactions of the RIIβ isoform with the PKA catalytic (C) subunit were analyzed by amide H/2H exchange mass spectrometry to compare solvent accessibility of RIIβ and the C subunit in their free and complexed states. Direct mapping of the RIIβ-C interface revealed important differences between the intersubunit interfaces in the type I and type II holoenzyme complexes. These differences are seen in both the R-subunits as well as the C-subunit. Unlike the type I isoform, the type II isoform complexes require both cAMP-binding domains, and ATP is not obligatory for high affinity interactions with the C-subunit. Surprisingly, the C-subunit mediates distinct, overlapping surfaces of interaction with the two R-isoforms despite a strong homology in sequence and similarity in domain organization. Identification of a remote allosteric site on the C-subunit that is essential for interactions with RII, but not RI subunits, further highlights the considerable diversity in interfaces found in higher order protein complexes mediated by the C-subunit of PKA.

Original languageEnglish (US)
Pages (from-to)487-499
Number of pages13
JournalJournal of Molecular Biology
Volume374
Issue number2
DOIs
StatePublished - Nov 23 2007

All Science Journal Classification (ASJC) codes

  • Structural Biology
  • Molecular Biology

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