Related Experiment Video
Updated: Aug 11, 2026

Chromatin Immunoprecipitation Assay for the Identification of Arabidopsis Protein-DNA Interactions In Vivo
Published on: January 14, 2016
Arabidopsis GIGANTEA protein is post-transcriptionally regulated by light and dark
Karine M David1, Ute Armbruster, Nga Tama
1School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand.
Abstract:
GIGANTEA (GI) is a key regulator of photoperiodic flowering in Arabidopsis and encodes a protein with no domains of known biochemical function. Expression of GI mRNA is controlled by the circadian clock, but GI protein accumulation has not been previously investigated. We generated plants that produced functional epitope-tagged GI to enable us to track the protein through the daily cycle. Here we show that GI protein levels oscillate when either constitutively overexpressed or driven by its promoter and that its accumulation is modulated by day length as well as by phase-specific factors. Also, we demonstrate that one of the mechanisms underlying GI protein oscillation occurs post-translationally via dark-induced proteolysis by the 26S proteasome.
Related Concept Videos
Cell Signaling in Plants
Biological Clocks and Seasonal Responses
Photoreceptors and Plant Responses to Light
Gene Regulation During Sporulation
The Antenna Complex
Regulation of Expression at Multiple Steps

