Inositol 1,4,5-Trisphosphate Receptor binding protein is a ubiquitous protein involved in the Ca2+ signalling processes in a variety of organisms [1]. The specific type of inositol 1,4,5-trisphosphate receptor (InsP3R) protein discussed here is the mouse type 1 InsP3R, also called InsP3R1. This polypeptide contains three major regions: the inositol 1,4,5-trisphosphate (InsP3) binding region, the central modulatory region, and the .[1] The protein forms an L-shaped structure composed of two asymmetric domains perpendicular to each other.[1] The N-terminal domain is made up of 12 β-strands and 2 single-turn helices, which come together to form a barrel.[1] The C-terminal end is quite different, consisting of a bundle made of eight α-helices.[1] The interface of the two domains is lined with basic residues and forms the for InsP3.[1] The InsP3R protein does not belong to a superfamily of proteins. The receptor is thought to span the membrane 6 times, leaving the C-terminus in the cytoplasm.[2]
