Ser175 phosphorylation of CDK9 is rapidly induced by T-cell activation signals.

Abstract

<p>(A) Affinity purification of FLAG-CDK9 complexes from Jurkat 2D10 cells and their identification by mass spectrometry. The percent values indicate the sequence coverage of the identified proteins. (B) Manually annotated MS/MS fragmentation spectra of the unmodified (upper) and phosphorylated (lower) CDK9 AFSLAK tryptic precursor peptides. (C) Ratio of phosphorylation of CDK9 at Ser175 and Thr186 in PMA stimulated (50 ng/ml) versus untreated cells with or without pretreatment with 20 µM U0126.</p