High impact information on TTG1

• In the seed coat, TTG2 expression requires TTG1 function in the production of tannin [1].
• Parallel analysis of the ttg1-1 mutant phenotype indicated that this mutant showed more severe developmental defects than myb61 and suggested that MYB61 may function in a genetic pathway distinct from that of TTG1 [2].
• TT8 and TTG1 were characterized recently and found to code for a basic helix-loop-helix domain transcription factor and a WD-repeat-containing protein, respectively [3].
• The protein is similar to AN11, a regulator of anthocyanin biosynthesis in petunia, and more distantly related to those of the beta subunits of heterotrimeric G proteins, which suggests a role for TTG1 in signal transduction to downstream transcription factors [4].
• The TRANSPARENT TESTA GLABRA1 (TTG1) locus regulates several developmental and biochemical pathways in Arabidopsis, including the formation of hairs on leaves, stems, and roots, and the production of seed mucilage and anthocyanin pigments [4].

Biological context of TTG1

• In the case of ttg1-21, it was found that a break occurred at the TTG1 locus on chromosome 5, and reciprocal translocation took place between it and chromosome 3 [5].
• It therefore appears that one of the functions of FUS3 is to restrict the domain of expression of TTG1 during embryogenesis [6].
• Moreover, the epidermal morphogenesis regulator TRANSPARENT TESTA GLABRA1 (TTG1) is negatively regulated by FUS3 in the embryo [6].
• By comparing the gene expression patterns of wild-type (Ler) and ttg1-1 mutant plants after gamma-irradiation, we identified various TTG1-regulated gamma-response genes [7].
• In support of this hypothesis, it was found that ectopic expression of GL1 in the presence of ectopic expression of the maize R gene, which can bypass the requirement for TTG, can ectopically activate GL2 transcription [8].

Anatomical context of TTG1

• Furthermore, although TT2 and TT8 were able to bind to the BAN promoter when simultaneously expressed in yeast, the activity of the complex correlated with the level of TTG1 expression in A. thaliana protoplasts [9].

Associations of TTG1 with chemical compounds

• Our results suggest that the TT8, TTG1, and TT2 proteins may interact to control flavonoid metabolism in the Arabidopsis seed coat [10].
• A model is proposed in which the patterning of root epidermal cells in Arabidopsis is regulated by the cell position-dependent action of the TTG/GL2 pathway, and the ethylene and auxin hormone pathways act to promote root hair outgrowth at a relatively late stage of differentiation [11].
• Potential translation initiation at conserved ATA (isoleucine) and TTG (leucine) codons is discussed [12].

Regulatory relationships of TTG1

• TT8 controls its own expression in a feedback regulation involving TTG1 and homologous MYB and bHLH factors, allowing a strong and cell-specific accumulation of flavonoids in Arabidopsis thaliana [13].

Other interactions of TTG1

• GLABRA3 (GL3) encodes a bHLH protein that interacts with the WD repeat protein, TTG1 [14].
• GL3 encodes a bHLH protein that regulates trichome development in arabidopsis through interaction with GL1 and TTG1 [15].
• The FUS3 transcription factor functions through the epidermal regulator TTG1 during embryogenesis in Arabidopsis [6].

Analytical, diagnostic and therapeutic context of TTG1

• Sequence analysis of six mutant alleles has identified base changes producing truncations or single amino acid changes in the TTG1 protein [4].

References