Inositol 1,4,5-trisphosphate receptor in the liver: Expression and function

Figure 4 Inositol 1,4,5-trisphosphate receptor structure. A: Linear structure of inositol 1,4,5-trisphosphate receptor (ITPR). The inositol 1,4,5-trisphosphate (InsP₃)-binding domain is located on the N-terminal region and the pore channel is on the C-terminal region. The receptor spans organelle membrane six times; B: Tridimensional view of ITPR showing that the receptor is formed by a 4 single chain. It is necessary that four InsP₃ molecules bind to the receptor to lead the calcium releases by a pore of the channel. The tridimensional structure was adapted from Molecular Modeling Database (National Center for Biotechnology Information). ER: Endoplasmic reticulum; ITPR: Inositol 1,4,5-trisphosphate receptor; NR: Nucleoplasmic reticulum.