Dear Sutanuka Das,

Have you read this paper (fruit fly):

"Dual-functioning transcription factors in the developmental gene network of Drosophila melanogaster"

https://bmcbioinformatics.biomedcentral.com/articles/10.1186/1471-2105-11-366

The authors stated: ........"To achieve this, we investigate the evidence for one or more Transcription factors (TFs) to have dual function, that is, function as activator for some CRMs and as repressor for others."

Dear Zoë P. Van Acker and Yuan-Yeu Yau, 

Thanks a lot for your inputs. I shall definitely look into these areas. I was particularly interested in the proteins of eukaryotic viruses. If there is any such class of proteins known in them. Anyways, thanks...

Dear Sutanuka Das,

Transcription factors usually work as activators, but they can also contribute to transcriptional repression. Of course, a possibility is the one you mention, i.e., the post-translational modifications, but there are also some other ways. For instance, EGR1, the product of an immediate-early gene, is an activator of many genes, but the protein possess a domain which binds the co-repressors NAB1/2 and, once recruited these co-repressors, the target gene is repressed. Due to this mechanism, the genes activated by EGR1 are only transiently induced. You may find further details in two papers of ours (Tur et al. (2010)  Factor binding and chromatin modification in the promoter of murine Egr1 gene upon induction. Cell. Mol. Life Sci. 67:4065–4077; Riffo-Campos et al. (2015) Nucleosome-specific, Time-dependent Changes in Histone Modifications during Activation of the Early Growth Response 1 (Egr1) Gene. J. Biol. Chem. 290:197–208), which are uploaded in my Research Gate profile.

All the best,

Luis Franco, Ph. D. Emeritus Professor of Biochemistry and Molecular Biology. University of Valencia and Institute of Health Research INCLIVA. Valencia, Spain

Dear Dr Franco,

Great to hear from you. I shall definitely look into your articles. Thanks for your input