Cell differentiation reflects the balance of two opposing influences, pathways which confer specialized properties on specific cells or groups of cells, and antagonising mechanisms which modulate responsiveness to such differentiative cues. It appears that the zinc finger protein Tramtrack (Ttk) fulfils the latter function in the CNS and PNS of Drosophila. Ttk seems to be able to inhibit neural development by down-regulating competence to respond to neuralising signals. We speculate, however, that restriction of neural competence is merely one example of a more general ability of Ttk to influence differentiation and that, given its widespread expression profile, Ttk might be implicated in a number of differentiative events.

This article has been cited by other articles:

				C. Mitchelmore, K. M. Kjarulff, H. C. Pedersen, J. V. Nielsen, T. E. Rasmussen, M. F. Fisker, B. Finsen, K. M. Pedersen, and N. A. Jensen Characterization of Two Novel Nuclear BTB/POZ Domain Zinc Finger Isoforms. ASSOCIATION WITH DIFFERENTIATION OF HIPPOCAMPAL NEURONS, CEREBELLAR GRANULE CELLS, AND MACROGLIA J. Biol. Chem., February 22, 2002; 277(9): 7598 - 7609. [Abstract] [Full Text] [PDF]

				P. Badenhorst Tramtrack controls glial number and identity in the Drosophila embryonic CNS Development, October 15, 2001; 128(20): 4093 - 4101. [Abstract] [Full Text] [PDF]

				Y. Wen, D. Nguyen, Y. Li, and Z.-C. Lai The N-terminal BTB/POZ Domain and C-Terminal Sequences Are Essential for Tramtrack69 to Specify Cell Fate in the Developing Drosophila Eye Genetics, September 1, 2000; 156(1): 195 - 203. [Abstract] [Full Text]

				F. Lehembre, P. Badenhorst, S. Müller, A. Travers, F. Schweisguth, and A. Dejean Covalent Modification of the Transcriptional Repressor Tramtrack by the Ubiquitin-Related Protein Smt3 in Drosophila Flies Mol. Cell. Biol., February 1, 2000; 20(3): 1072 - 1082. [Abstract] [Full Text]

				Z.-C. Lai and Y. Li Tramtrack69 Is Positively and Autonomously Required for Drosophila Photoreceptor Development Genetics, May 1, 1999; 152(1): 299 - 305. [Abstract] [Full Text]

				G. Roesijadi, R. Bogumil, M. Vasak, and J. H. R. Kagi Modulation of DNA Binding of a Tramtrack Zinc Finger Peptide by the Metallothionein-Thionein Conjugate Pair J. Biol. Chem., July 10, 1998; 273(28): 17425 - 17432. [Abstract] [Full Text] [PDF]