Wagner, D, Sablowski RW. 2001. Glucocorticoid Fusions for Transcription Factor. In Arabidopsis-A Laboratory Manual. (Weigel, D., Glazebrook, J., Eds.)., Cold Spring Harbor: Cold Spring Harbor Laboratory Press.
This system was pioneered in plants by Alan Lloyd . Plant cognate
homologues of hsp90 are thought to bind to the glucocorticoid (GR) receptor fusion
protein in the absence of hormone, thus retaining it in the cytoplasm. Upon hormone
treatment the fusion protein detaches from hsp90 and enters the nucleus. This type
of induction has thus far been used primarily to induce transcriptional regulators in plants
[4-6] although cytoplasmic proteins can also be controlled using this system. The
GR fusion has several useful craracteristics:
A. The regulation is tight: little or no activation is found in the absence of hormone
B. Since induction is post-translational, it allows for the use of protein synthesis
inhibitors together with hormone induction to test for direct downstream events.
C. The post-transcriptional switch allows free choice of promoters to combine temporal
control by steroid with tissue-specific expression.
D. Activation can be transient or sustained by repeated steroid treatment.
E. No side effects of the steroid hormone treatment have been observed in plants.