Smalle et al. (1998): GT-2 is a plant transcriptional activator that contains two separate, but similar, trihelix DNA-binding domains. GT-1 is similar to GT-2, although it contains only one of such domains. cDNAs that encode GT-2 were isolated from rice (OS-GT2) and Arabidopsis (AT-GT2). Evidence is presented for the existence of an Arabidopsis gene family that is structurally related to AT-GT2. Two members of this GT2-like family, AT-GTL1 and AT-GTL2, have been isolated and characterized. Their sequences suggest that they evolved by a recent gene duplication event. Both AT-GT2 and AT-GTL genes contain an intron in the amino-terminal trihelix motif, indicating that this DNA-binding domain resulted from exon shuffling. RNA gel blot analysis using AT-GTL1 as a probe revealed four transcripts in the aerial part of the plant. All mRNA levels were significantly higher in siliques, suggesting that this gene family may function in fruit and/or seed development. To date, DNA-binding proteins characterized by the trihelix motif have been described only in plants, and may therefore be involved in plant-specific processes. Our results show that in Arabidopsis thaliana, the trihelix motif is not restricted to the GT-1 and GT-2 DNA-binding proteins.

Kaplan-Levy et al. (2012): GT factors are the founding members of the trihelix transcription factor family. Genomic studies have revealed 30 members of this family in Arabidopsis and 31 in rice, falling into five clades. Newly discovered functions involve responses to salt and pathogen stresses, the development of perianth organs, trichomes, stomata and the seed abscission layer, and the regulation of late embryogenesis.


1) Kaplan-Levy, RN; Brewer, PB; Quon, T; Smyth, DR. 2012. The trihelix family of transcription factors--light, stress and development. Trends Plant Sci. 17(3):163-71 PubMed
2) Nagano, Y. 2000. Several features of the GT-factor trihelix domain resemble those of the Myb DNA-binding domain. Plant Physiol. 124(2):491-4 PubMed
3) Nagano, Y; Inaba, T; Furuhashi, H; Sasaki, Y. 2001. Trihelix DNA-binding protein with specificities for two distinct cis-elements: both important for light down-regulated and dark-inducible gene expression in higher plants. J. Biol. Chem. 276(25):22238-43 PubMed
4) Smalle, J; Kurepa, J; Haegman, M; Gielen, J; Van Montagu, M; Van Der Straeten, D. 1998. The trihelix DNA-binding motif in higher plants is not restricted to the transcription factors GT-1 and GT-2. Proc. Natl. Acad. Sci. U.S.A. 95(6):3318-22 PubMed
5) Zhou, DX. 1999. Regulatory mechanism of plant gene transcription by GT-elements and GT-factors. Trends Plant Sci 4(6):210-214 PubMed


Name: Trihelix
Class: TF
Number of species containing the TAP: 97
Number of available proteins: 3032

The colour code corresponds to the rules for the domains:

should be contained
should not be contained

Domain rules:

(Domain names are clickable)

Phylogenetic tree for Archeaplastida:

To view the tree click here.

TAP distribution:

The following table shows the distribution of Trihelix over all species included in TAPscan. The values for e.g. a specific kingdom are shown in the tree below if you expand the tree for that kingdom.

Minimum Maximum Average Median Standard deviation

List of species containing Trihelix sorted by kingdomcladesupergrouporderfamily:

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expand kingdom Archaeplastida (3088 proteins in 97 species)