ATRAID (All-trans retinoic acid-induced differentiation factor), also known as APR3, is a membrane protein that functions as a proliferation suppressor. It plays a role in inducing the cell cycle arrest via inhibiting CCND1 expression in all-trans-retinoic acid (ATRA) signal pathway [, ].
Augurin is alternatively named oesophageal cancer-related gene 4 protein. The function of this family of transmembrane proteins is to induce the senescence of oligodendrocyte and neural precursor cells, characterised by G1 arrest, RB1 dephosphorylation and accelerated CCND1 and CCND3 proteasomal degradation [, ]. Augurin is a posible hormone that has been found to stimulate the release of adrenocorticotropic hormone (ACTH) via the release of hypothalamic corticotrophin-releasing factor (CRF) [].
This entry includes UHRF1/2 from animals and ORTHRUS 1-5 from Arabidopsis. They are ubiquitin-like proteins with PHD and RING finger domains. UHRF1, also known as ICBP90, is a transcription and cell cycle regulator and a methyl K9 H3-specific binding protein []. UHRF2 is a ubiquitin E3 ligase for cell cycle proteins, such as CCND1 and CCNE1 []. It can also act as a SUMO E3 ligase for ZNF131 []. This family also includes UHRF1-like protein from Cryptococcus neoformans, which binds hemimethylated DNA and is involved in DNA methylation maintenance. Unlike the human orthologue, UHRF1-like lacks the Tudor H3K9me reader and RING E3 ligase domains found in its human ortholog [].In plants, ORTHRUS family members are E3 ligases mediating DNA methylation status in vivo. ORTH1-ORTH5 are predicted to encode proteins that contain one plant homeodomain (PHD), two really interesting new gene (RING) domains, and one set ring associated (SRA) domain [].
