This domain corresponds to the ligand binding region on inositol 1,4,5-trisphosphate receptor, and the N terminal region of the ryanodine receptor. Both receptors are involved in Ca2+ release. They can couple to the activation of neurotransmitter-gated receptors and voltage-gated Ca2+ channels on the plasma membrane, thus allowing the endoplasmic reticulum discriminate between different types of neuronal activity [1].

1: Crystal structure of the ligand binding suppressor domain of type 1 inositol 1,4,5-trisphosphate receptor. Bosanac I, Yamazaki H, Matsu-Ura T, Michikawa T, Mikoshiba K, Ikura M; Mol Cell. 2005;17:193-203. PMID:15664189

2: The role of the endoplasmic reticulum Ca2+ store in the plasticity of central neurons. Bardo S, Cavazzini MG, Emptage N; Trends Pharmacol Sci. 2006;27:78-84. PMID:16412523