Protein sel-1 homolog 1 is a protein that in humans is encoded by the SEL1L gene. May play a role in Notch signaling. May be involved in the endoplasmic reticulum quality control (ERQC) system also called ER-associated degradation (ERAD) involved in ubiquitin-dependent degradation of misfolded endoplasmic reticulum proteins. In mammals, the most well-characterized ERAD machinery is the highly conserved complex of suppressor-enhancer of lin-12–like and hydroxymethylglutaryl-CoA reductase degradation protein 1 (SEL1L-HRD1), which consists of the E3 ubiquitin ligase HRD1 and its adaptor protein SEL1Lc.The Sel1L-deficient experimental model of central diabetes insipidus is unlikely to be observed in humans, as Sel1L loss is embryonically lethal. Three-week-old mice with Sel1L deficiency specifically in AVP neurons (Sel1LAVP mice) lacked AVP-positive transport vesicles in axons, a phenotype that explains the development of the central diabetes insipidus phenotype in these mice.