SPOC (Spen paralog and ortholog C-terminal) domain found in some death-inducer obliterator variants
The Dido/DIDO1 gene has been implicated in several cellular processes such as apoptosis and chromosomal segregation, particularly in the hematopoietic system. It encodes alternative splicing variants, including Dido1, 2, and 3, with Dido3 being the longest isoform and Dido1 being the shortest. Dido3 is ubiquitously expressed in all human tissues, is dispensable for embryonic stem (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. Dido2 and Dido1 are truncated at the C-terminus relative to Dido3, with Dido2 containing a partial SPOC domain whereas Dido1 is missing it completely. Dido1, also called DIO-1, or death-associated transcription factor 1 (DATF-1), is important for maintaining ES cells and directly regulates the expression of pluripotency factors. The conserved plant homeodomain (PHD) finger is responsible for the binding of histone H3 with a higher affinity for trimethylated lysine 4 (H3K4me3). The Dido/DIDO1 gene is a bone morphogenetic protein (BMP) target gene, which promotes BMP-induced melanoma progression. It also triggers apoptosis after nuclear translocation and caspase upregulation. This model corresponds to the SPOC domain which is involved in developmental signaling and has also been proposed to be a phosphorylation binding module.
Jiyao W et al.(2023). "The conserved domain database in 2023.",