ITPR1 and Huntington disease: Previous data shows that mutant huntingtin can modulate calcium signaling in neuronal cells through an interaction with IP3R1,18 and hat IP3R1 is negatively regulated in a mouse model for HD.19 Sig-1R is enriched within the MAM region in the ER13 and influences Ca2+ signaling from ER into mitochondria by stabilizing IP3R.