inositoli145trifosfaattia

Inositoli145trifosfaattia, also known as inositol 1,4,5-trisphosphate (IP3) or D-myo-inositol 1,4,5-trisphosphate, is a naturally occurring molecule that plays a crucial role as a second messenger in intracellular signal transduction pathways. It is a derivative of inositol, a cyclic six-carbon alcohol, and is phosphorylated at the 1, 4, and 5 positions of its ring structure.

IP3 is synthesized in the cell's plasma membrane in response to extracellular signals, such as hormones or neurotransmitters. These signals activate specific enzymes, typically phospholipase C, which then cleave a membrane phospholipid called phosphatidylinositol 4,5-bisphosphate (PIP2) into two signaling molecules: diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3).

Once released into the cytoplasm, IP3 diffuses and binds to specific IP3 receptors located on the endoplasmic reticulum, a cellular organelle responsible for calcium storage. This binding triggers the opening of calcium channels on the endoplasmic reticulum membrane, leading to a rapid release of stored calcium ions into the cytoplasm. The increase in cytoplasmic calcium concentration then activates various downstream cellular processes, including muscle contraction, neurotransmitter release, gene expression, and metabolic regulation. The precise cellular response depends on the specific cell type and the signaling pathway involved.