• OMIM: 604 708
  • MGI: 1859333

Toni City - Responsive Enhancer Binding Protein ( TonEBP or NFAT5/OREBP ) is a transcription factor that belongs to the Rel family of transcription factors. TonEBP protects cells from hypertonic stress. Is the osmolar pressure of the cell in normal ( isoosmolar situation ) is TonEBP only partially (partially) activated. Increases the osmolar pressure of the cell, the TonEBP mRNA is stabilized and the TonEBP protein transcribed thus enhanced. TonEBP promotes the transcription of the genes of different proteins, such as aldose reductase, sodium -myo -inositol cotransporter, sodium chloride cotransporter betaine, and taurine transporter. This leads to an increase in the concentration of molecules sorbitol, betaine, myo-inositol and taurine in the cell. These molecules are osmotically active ( osmolytes ) and electrically neutral, an increase in their concentration therefore reduces the osmotic pressure on the cell wall and the ionic strength in the cell. In addition, TonEBP stimulates transcription of the genes of ADH - regulated urea transporter and heat shock proteins. These proteins protect the cell against the harmful effects of high urea concentrations. In the kidney, TonEBP promotes transcription of the aquaporin water channel or AQP2. This increases the excretion of water from the concentration of the urine increases, and the osmolarity of the extracellular fluid decreases.


  • Transcription factor
  • Cell Biology
  • Nephrology