乙酰胆碱调节胰岛素分泌
中文名称
通路描述
由副交感神经末梢释放的乙酰胆碱在葡萄糖浓度大于约7毫摩尔时，能引起胰岛β细胞中胰岛素释放的显著增强。乙酰胆碱结合胰腺β细胞上的M3型乙酰胆碱受体。结合作用有两个效应：通过未知机制增加细胞对钠离子的通透性，以及通过异三聚体G蛋白G(q)激活磷脂酶Cβ-1。
英文描述
Acetylcholine regulates insulin secretion Acetylcholine released by parasympathetic nerve endings in the pancreas causes a potentiation of insulin release when glucose is present at concentrations greater than about 7 mM. Acetylcholine binds the Muscarinic Acetylcholine Receptor M3 on pancreatic beta cells. The binding has two effects: an increase in permeability of the cell to Na+ ions through an unknown mechanism, and the activation of Phospholipase C beta-1 through a heterotrimeric G protein, G(q).
After acetylcholine binds the Muscarinic Acetycholine Receptor M3, the receptor activates the G protein Gq by causing the alpha subunit of Gq to exchange GDP for GTP. Activation of Gq in turn activates Phospholipase C beta-1. Phospholipase C beta-1 hydrolyzes the phosphodiester bond at the third position of phosphoinositol 4,5-bisphosphate, producing diacylglycerols (DAG) and inositol 1,4,5-trisphosphate.
DAG remains in the cell membrane and causes Protein Kinase C alpha (PKC alpha) to translocate from the cytosol to the membrane. This results in the activation of PKC alpha which then phosphorylates target proteins on serine and threonine residues. One known target of PKC alpha is Myristoylated Alanine-rich C Kinase Substrate (MARCKS), which is believed to affect vesicle transport and may be responsible for the increased traffic of insulin granules seen in response to acetylcholine.
Inositol trisphophate binds a receptor, the IP3 receptor, on calcium stores in the cell (probably the endoplasmic reticulum). The release of calcium into the cytosol stimulates the exocytosis of insulin granules.
After acetylcholine binds the Muscarinic Acetycholine Receptor M3, the receptor activates the G protein Gq by causing the alpha subunit of Gq to exchange GDP for GTP. Activation of Gq in turn activates Phospholipase C beta-1. Phospholipase C beta-1 hydrolyzes the phosphodiester bond at the third position of phosphoinositol 4,5-bisphosphate, producing diacylglycerols (DAG) and inositol 1,4,5-trisphosphate.
DAG remains in the cell membrane and causes Protein Kinase C alpha (PKC alpha) to translocate from the cytosol to the membrane. This results in the activation of PKC alpha which then phosphorylates target proteins on serine and threonine residues. One known target of PKC alpha is Myristoylated Alanine-rich C Kinase Substrate (MARCKS), which is believed to affect vesicle transport and may be responsible for the increased traffic of insulin granules seen in response to acetylcholine.
Inositol trisphophate binds a receptor, the IP3 receptor, on calcium stores in the cell (probably the endoplasmic reticulum). The release of calcium into the cytosol stimulates the exocytosis of insulin granules.
所含基因
10 个基因