Transcriptional corepressor. Recruits NR2E1 to repress transcription. Promotes vascular smooth cell (VSMC) migration and orientation (By similarity). Corepressor of MTG8 transcriptional repression. Has some intrinsic repression activity which is independent of the number of poly-Gln (polyQ) repeats. Interacts with NR2E1; the interaction represses the transcriptional activity of NR2E1. Interacts (via its N-terminus) with FAT1 (via a C-terminal domain) (By similarity). Interacts with BAIAP2, WWP1, WWP2, WWP3 and RERE. Interacts (via its N-terminus) with MTG8; the interaction enhances transcriptional repression of MTG8. Interacts with PQBP1. Shuttles between nucleus and cytoplasm. Colocalizes with FAT1 in the perinuclear area, at cell-cell junctions and leading edges of cells (By similarity). Colocalizes with MTG8 in discrete nuclear dots. Proteolytic fragment F1 appears to remain in nucleus. Fragment F2 is exported into the cytoplasm. Fragment F2 from mutant sequences with longer poly-Gln (polyQ) tracts are additionally located to the cytoplasmic membrane and to certain organelles. Widely expressed in various tissues including heart, lung, kidney, ovary, testis, prostate, placenta, skeletal Low levels in the liver, thymus and leukocytes. In the adult brain, broadly expressed in amygdala, caudate nucleus, corpus callosum, hippocampus, hypothalamus, substantia nigra, subthalamic nucleus, and thalamus. High levels in fetal tissues, especially brain. The HX repeat motif is a specific pH-dependent interaction motif for ions and/or proteins or other biomolecules. This motif could be involved in the control of embryonic development. Phosphorylated in vitro by MAPK8/JNK1 on Ser-739. Mutant ATN1 sequences with expanded poly-Gln (polyQ) traits are more slowly phosphorylated. Proteolytically cleaved, probably in the nucleus, to produce two C-terminal fragments of 140 kDa (F1) and 125 kDa (F2) each containing poly-Gln (polyQ) tracts. F2 is produced by cleavage by caspases and is exported into the cytoplasm. In vitro, cleavage increases with an increase in the number of polyQ tracts. C-terminal proteolytic products appear to be the cause of cell toxicity. In vitro cleavage at Asp-109. The poly-Gln region of ATN1 is highly polymorphic (7 to 23 repeats) in the normal population and is expanded to about 49-75 repeats in DRPLA and HRS patients. Longer expansions result in earlier onset and more severe clinical manifestations of the disease. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry.