PHD finger found in PHD finger protein 3 (PHF3), and death-inducer obliterator variants Dido1, Dido2, and Dido3
PHF3 is a human homolog of yeast protein bypass of Ess1 (Bye1), a nuclear protein with a domain resembling the central domain in the transcription elongation factor TFIIS. It is ubiquitously expressed in normal tissues including brain, but its expression is significantly reduced or lost in glioblastomas. PHF3 contains an N-terminal plant homeodomain (PHD) finger, a central RNA polymerase II (Pol II)-binding TFIIS-like domain (TLD) domain, and a C-terminal Spen paralogue and orthologue C-terminal (SPOC) domain. This family also includes Dido gene encoding three alternative splicing variants (Dido1, 2, and 3), which have been implicated in a number of cellular processes such as apoptosis and chromosomal segregation, particularly in the hematopoietic system. Dido1 is important for maintaining embryonic stem (ES) cells and directly regulates the expression of pluripotency factors. It is the shortest isoform that contains only a highly conserved PHD finger responsible for the binding of histone H3 with a higher affinity for trimethylated lysine4 (H3K4me3). Gene Dido1 is a Bone morphogenetic protein (BMP) target gene and promotes BMP-induced melanoma progression. It also triggers apoptosis after nuclear translocation and caspase upregulation. Dido3 is the largest isoform and is ubiquitously expressed in all human tissues. It is dispensable for ES cell self-renewal and pluripotency, but is involved in the maintenance of stem cell genomic stability and tumorigenesis. Dido3 contains a PHD finger, a transcription elongation factor S-II subunit M (TFSIIM) domain, a SPOC module, and a long C-terminal region (CT) of unknown homology.
Jiyao W et al.(2023). "The conserved domain database in 2023.",