Linked Life Data

16546994

Source:http://linkedlifedata.com/resource/pubmed/id/16546994

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
2006-6-15
pubmed:abstractText
Multisite phosphorylation is an important mechanism for achieving intricate regulation of protein function. Here we extended the absolute quantification of abundance (AQUA) methodology and validated its applicability to quantitatively study multisite phosphorylation. As a test case, we chose the conserved inhibitory site of the cyclin-dependent kinases (CDKs), Cdk1, Cdk2, and Cdk3, which are important regulators of cell cycle transitions and apoptosis. Inhibitory phosphorylation at Thr(14) and Tyr(15) of the CDKs is modulated by complex regulatory mechanisms involving multiple kinases and phosphatases. Yet the resulting quantitative dynamics among the four possible phosphorylated and non-phosphorylated versions of CDKs (T14p-Y15p, T14p-Y15, T14-Y15p, and T14-Y15) has not been investigated to date. Hence we used the heavy isotope-labeled tryptic peptides spanning the inhibitory site as internal standards and quantified all four versions by LC-selected reaction monitoring. Quantification of the phosphorylation status of the inhibitory site in the cell extracts provided novel quantitative insights. 1) The transition to mitotic phase was dominated by the conversion of "T14p-Y15p" to the "T14-Y15" form, whereas the two monophosphorylated forms were considerably lower in abundance. 2) The amount of all four forms decreased during the progression of apoptosis but with differing kinetics. Analysis of immunoprecipitated Cdk1 and Cdk2 revealed that the inhibitory site phosphorylation state of both kinases at different stages of the cell cycle followed the same trend. Quantitative immunoblotting using antibodies to Cdk1 and Cdk2 and to the T14-Y15p form suggested that quantification by AQUA was reliable and accurate. These results highlight the utility of internal standard peptides to achieve accurate quantification of multisite phosphorylation status.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
1535-9476
pubmed:author
pubmed:issnType
Print
pubmed:volume
5
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1146-57
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
Absolute quantification of multisite phosphorylation by selective reaction monitoring mass spectrometry: determination of inhibitory phosphorylation status of cyclin-dependent kinases.
pubmed:affiliation
Department of Cell Biology and Center for Vascular Biology, University of Connecticut Health Center, Farmington, Connecticut 06030, USA.
pubmed:publicationType
Journal Article, Research Support, N.I.H., Extramural