Gibbs, E.B., Laremore, T.N., Usher, G.A., Portz, B., Cook, E.C., Showalter, S.A. (2017). Substrate Specificity of the Kinase P-TEFb towards the RNA Polymerase II C-Terminal Domain. Biophys. J. 113(9): 1909--1911.
FlyBase ID
FBrf0237137
Publication Type
Research paper
Abstract
The positive transcription elongation factor b (P-TEFb) promotes transcription elongation through phosphorylation of the RNA polymerase II C-terminal domain. This process is not well understood, partly due to difficulties in determining the specificity of P-TEFb toward the various heptad repeat motifs within the C-terminal domain. A simple assay using mass spectrometry was developed to identify the substrate specificity of the Drosophila melanogaster P-TEFb (DmP-TEFb) in vitro. This assay demonstrated that DmP-TEFb preferentially phosphorylates Ser5 and, surprisingly, that pre-phosphorylation or conserved amino acid variation at the 7-position in the heptad can alter DmP-TEFb specificity, leading to the creation of distinct double-phosphorylation marks.
