IP3 receptor
| IP3 receptor | ||
|---|---|---|
| Mass / length primary structure | 2758/2701/2671 amino acids | |
| Secondary to quaternary structure | Homotetramer; multipass membrane protein | |
| Isoforms | 8th | |
| Identifier | ||
| Gene name (s) | ITPR1 , ITPR2 , ITPR3 | |
| External IDs | ||
| Transporter classification | ||
| TCDB | 1.A.3.2.1 | |
| designation | Ryanodine / IP3 receptor calcium channel family | |
| Occurrence | ||
| Parent taxon | multicellular animals | |
The IP 3 receptor is a ligand-activated calcium channel in the membrane of the smooth endoplasmic reticulum (ER). Its specific ligand is inositol trisphosphate (abbreviated to IP 3 ).
function
IP 3 has the function of a so-called secondary messenger substance . It is one of the products of phospholipase C that is activated by binding specific ligands to G protein-coupled receptors .
IP 3 receptors are nonspecific cation channels , the rapid release of its opening in calcium - ion from the ER and thus an increase in cytoplasmic calcium concentration effect.
The IP 3 receptor has a high conductivity . Its single channel conductivity is greater than 200 pS .
The IP 3 receptor is a tetramer, i.e. four homomeric protein subunits form a functional channel. Each of these subunits has 6 transmembrane domains , each with a pore-forming loop between segments 5 and 6.
It was recently found that, in addition to the approximately 99% IP 3 receptors in the ER membrane, a few are expressed in the plasma membrane. In a mouse B-cell , for example, there are only 1–2 specimens. Nevertheless, they make a measurable contribution to the physiologically important influx of calcium into the cell.
literature
- I. Bosanac, H. Yamazaki, T. Matsu-Ura, T. Michikawa, K. Mikoshiba, M. Ikura: Crystal structure of the ligand binding suppressor domain of type 1 inositol 1,4,5-trisphosphate receptor. In: Mol. Cell. 17 (2), January 2005, pp. 193-203. doi: 10.1016 / j.molcel.2004.11.047 . PMID 15664189 .
- I. Bosanac, JR Alattia, TK Mal et al: Structure of the inositol 1,4,5-trisphosphate receptor binding core in complex with its ligand. In: Nature 420 (6916), December 2002, pp. 696-700. doi: 10.1038 / nature01268 . PMID 12442173 .
- Y. Yoshida, S. Imai: Structure and function of inositol 1,4,5-trisphosphate receptor. In: Jpn J Pharmacol . 74 (2), June 1997, pp. 125-137. doi: 10.1254 / jjp.74.125 . PMID 9243320 .
- S. Supattapone et al: Solubilization, purification, and characterization of an inositol trisphosphate receptor. In: J Biol Chem . 263 (3), 1988 Jan 25, pp. 1530-1534.