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.
J Mol Biol
; 374(2): 487-99, 2007 Nov 23.
Article
em En
| MEDLINE
| ID: mdl-17942118
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 RIIbeta isoform with the PKA catalytic (C) subunit were analyzed by amide H/(2)H exchange mass spectrometry to compare solvent accessibility of RIIbeta and the C subunit in their free and complexed states. Direct mapping of the RIIbeta-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.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Holoenzimas
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Deutério
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Subunidade RIalfa da Proteína Quinase Dependente de AMP Cíclico
/
Amidas
Idioma:
En
Ano de publicação:
2007
Tipo de documento:
Article