InterPro domain: IPR042010

ATX1 and -2 are sister paralogs originating from a segmental chromosomal duplication; they are plant counterparts of the Drosophila melanogaster trithorax (TRX) and mammalian mixed-lineage leukemia (MLL1) proteins [ 1 ]. ATX1 is a methyltransferase that trimethylates histone H3 at lysine 4 (H3K4me3). It also acts as a histone modifier and as a positive effector of gene expression [ 2 ]. ATX1 regulates transcription from diverse classes of genes implicated in biotic and abiotic stress responses. It is involved in dehydration stress signaling in both abscisic acid (ABA)-dependent and ABA-independent pathways [ 3 ]. ATX2 is involved in dimethylating histone H3 at lysine 4 (H3K4me2) [ 4 ]. ATX1 and ATX2 are multi-domain proteins that consist of an N-terminal PWWP domain, FYRN- and FYRC (DAST, domain associated with SET in trithorax) domains, a canonical PHD finger, a non-canonical ePHD finger, and a C-terminal SET domain [ 5 ].

This entry represents the PHD finger of A. thaliana histone-lysine N-methyltransferase arabidopsis trithorax-like proteins ATX1, -2, and similar proteins.

1. Two Arabidopsis homologs of the animal trithorax genes: a new structural domain is a signature feature of the trithorax gene family. Gene 271, 215-21
2. ATX1-generated H3K4me3 is required for efficient elongation of transcription, not initiation, at ATX1-regulated genes. PLoS Genet. 8, e1003111
3. The Arabidopsis trithorax-like factor ATX1 functions in dehydration stress responses via ABA-dependent and ABA-independent pathways. Plant J. 66, 735-44
4. The highly similar Arabidopsis homologs of trithorax ATX1 and ATX2 encode proteins with divergent biochemical functions. Plant Cell 20, 568-79
5. Evolution of the PWWP-domain encoding genes in the plant and animal lineages. BMC Evol. Biol. 12, 101