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.
Original language | English |
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Pages (from-to) | 721-730 |
Number of pages | 9 |
Journal | Biological Chemistry |
Volume | 377 |
Issue number | 11 |
Publication status | Published - Nov 1996 |
Keywords
- c-Myb inhibitor
- c-Myb regulation
- Mitogen activated protein kinases
- Phosphopeptide mapping
- Serum stimulation
- Transcriptional activation