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Updated: Aug 14, 2026

Assaying Protein Kinase Activity with Radiolabeled ATP
Published on: May 26, 2017
Functional analysis of phosphorylation at serine 532 of human c-Myb by MAP kinase
G Vorbrueggen1, J Lovrić, K Moelling
1Institut für Medizinische Virologie, Universität Zürich, Switzerland.
Abstract:
The c-myb proto-oncogene encodes a transcription factor that is implicated in regulatory events during hematopoiesis. It contains negative regulatory domains at both the amino- and carboxy-termini. Here we describe that human c-Myb can be phosphorylated by mitogen-activated protein kinases (MAPK's) at serine 532 of the carboxy (C-) terminal regulatory domain in vitro. This serine residue can also be phosphorylated in vivo upon serum-stimulation of Jurkat cells. Expression of a constitutively active form of Ras together with c-Myb in transient transfection experiments had no effect on the transcriptional activity of c-Myb, while expression of a polypeptide containing the c-Myb C-terminal domain stimulated c-Myb activity. This effect is reduced upon MAPK-dependent phosphorylation of serine 532. Our data suggest that the MAPK-dependent state of phosphorylation modifies the cellular function of c-Myb by modulating its interaction with a putative inhibitory factor.
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