RARRES3 (retinoic acid receptor responder (tazarotene induced) 3)

	Schematic of the TIG3 gene. Thick red boxes indicate exons.
Description	DNA size: 9658 bp with 4 exons.
Transcription	mRNA size: 779 bp, processed: 495 bp.

Note	The C-terminus of TIG3 is believed to be a membrane-anchoring domain which is involved in driving membrane localization and is also required for centrosome localization. Removal of this domain from TIG3 causes it to distribute diffusely throughout the cytoplasm and reduces its ability to decrease cell survival (Deucher et al., 2000; Sturniolo et al., 2003; Sturniolo et al., 2005; Jans et al., 2008; Tsai et al., 2009).
	Schematic of the TIG3 protein. The purple indicates the hydrophilic N-terminus (amino acids 1-134) and green indicates the hydrophobic C-terminus (amino acids 134-164). The orange regions represent conserved elements with the H-rev107 family. Highly conserved regions are labeled.
Description	164 amino acids; 18 kDa protein; contains a hydrophilic N-terminus (1-134) and hydrophobic, membrane-anchoring domain (134-164).
Expression	Ubiquitously expressed; expression is reduced in hyperproliferative diseases including cancer.
Localisation	Cell membrane, centrosome (Scharadin et al., 2011).
Function	TIG3 is a type II tumor suppressor gene which regulates cell proliferation and survival (DiSepio et al., 1998). Loss of TIG3 expression leads to hyperproliferative diseases including psoriasis and cancer. Restoration of TIG3 expression to cancer cell lines decreases cell cycle progression and induces apoptosis causing an overall decrease in viable cells (DiSepio et al., 1998; Huang et al., 2002; Higuchi et al., 2003; Tsai et al., 2009; Scharadin et al., 2011). Localization of TIG3 to the centrosome is believed to be responsible for this decrease in cell survival, which leads to an increase in p21 level, a G1/S phase block, an activation of the caspase cascade, and a reorganization of the microtubule network (Scharadin et al., 2011). In contrast, expression of TIG3 in normal keratinocytes induces a process of terminal differentiation through the binding to and activation of type I transglutaminase and increase in cornified envelope formation to decrease cell survival (Sturniolo et al., 2003; Sturniolo et al., 2005; Jans et al., 2008). Localization of TIG3 to the cell membrane in keratinocytes is necessary for it to bind type I transglutaminase.
Homology	TIG3 shares homology with the H-rev107 family of class II tumor suppressors and the NlpC/P60 superfamily (Hajnal et al., 1994; DiSepio et al., 1998; Husmann et al., 1998; Anantharaman and Aravind, 2003; Jahng et al., 2003).

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