What does inositol triphosphate do?

IP3’s main functions are to mobilize Ca2+ from storage organelles and to regulate cell proliferation and other cellular reactions that require free calcium. In smooth muscle cells, for example, an increase in concentration of cytoplasmic Ca2+ results in the contraction of the muscle cell.

What is the function of the IP3 receptor?

The IP3R [IP3 (inositol 1,4,5-trisphosphate) receptor] is responsible for Ca2+ release from the ER (endoplasmic reticulum). We have been working extensively on the P400 protein, which is deficient in Purkinje-neuron-degenerating mutant mice.

Is IP3 a second messenger?

Inositol 1,4,5-triphosphate (IP3) is a second messenger that binds to the IP3 receptor encoded by ITPR1 (van de Leemput et al., 2007 ).

What does IP3 do to calcium ions?

It is well known that the IP3 pathway is important and can release endoplasmic reticulum calcium to change intracellular calcium concentration. At present, much work has been done to show that the increase of intracellular calcium concentration mediated by the IP3 pathway is related to lipolysis.

Is IP3 a protein?

IP3R was identified to be P400 protein, a protein, which was missing in the cerebellum of ataxic mutant mice lacking Ca(2+) spikes in Pukinje cells. IP3R was an IP3 binding protein and was a Ca(2+) channel localized on the endoplasmic reticulum.

How is IP3 removed?

Fig. IP3 is deactivated by phosphorylation to IP4 or dephosphorylation to IP2. RyRs are close relatives of IP3Rs, but they are predominantly expressed in the sarcoplasmic reticulum of skeletal (RyR1) and cardiac (RyR2) muscle.

Does IP3 cause calcium release?

IP3 receptors and ryanodine receptors are the major calcium release channels that display CICR. These structurally related channels are widely expressed and mediate calcium release in muscle, neurons and non-excitable cells. IP3 dictates the sensitivity of IP3 receptors to calcium.

What is the IP3 pathway?

IP3 pathway: IP3 acts to release Ca2+ from the endoplasmic reticulum by binding to receptors that are ligand-gated Ca2+ channels. As a result, cytosolic Ca2+ levels increase to about 1 μM, which affects the activities of a variety of target proteins, including protein kinases and phosphatases.

When IP3 is released it will evoke the release of?

Inositol 1,4,5-trisphosphate (IP3) evokes release of Ca2+ from the endoplasmic reticulum (ER), but the resulting Ca2+ signals are shaped by interactions with additional intracellular organelles.