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The influx of Ca 2+ ions causes the secretion of insulin stored in vesicles through the cell membrane. The process of insulin secretion is an example of a trigger mechanism in a signal transduction pathway because insulin is secreted after glucose enters the beta cell and that triggers several other processes in a chain reaction.
Beta cells (β-cells) are specialized endocrine cells located within the pancreatic islets of Langerhans responsible for the production and release of insulin and amylin. [1] Constituting ~50–70% of cells in human islets, beta cells play a vital role in maintaining blood glucose levels. [ 2 ]
Proinsulin is synthesized on membrane associated ribosomes found on the rough endoplasmic reticulum, where it is folded and its disulfide bonds are oxidized. It is then transported to the Golgi apparatus where it is packaged into secretory vesicles, and where it is processed by a series of proteases to form mature insulin.
One of the uses of NADPH in the cell is to prevent oxidative stress. It reduces glutathione via glutathione reductase, which converts reactive H 2 O 2 into H 2 O by glutathione peroxidase. If absent, the H 2 O 2 would be converted to hydroxyl free radicals by Fenton chemistry, which can attack the cell. Erythrocytes, for example, generate a ...
PTMs are important components in cell signalling, as for example when prohormones are converted to hormones. Post-translational modifications can occur on the amino acid side chains or at the protein's C-or N-termini. [1] They can expand the chemical set of the 22 amino acids by changing an existing functional group or adding a new one such as ...
Insulin and glucagon are the primary hormones involved in maintaining a steady level of glucose in the blood, and the release of each is controlled by the amount of nutrients currently available. [17] The amount of insulin released in the blood and sensitivity of the cells to the insulin both determine the amount of glucose that cells break ...
Circulating insulin also affects the synthesis of proteins in a wide variety of tissues. It is thus an anabolic hormone, promoting the conversion of small molecules in the blood into large molecules in the cells. Low insulin in the blood has the opposite effect, promoting widespread catabolism, especially of reserve body fat.
The insulin receptor (IR) is a transmembrane receptor that is activated by insulin, IGF-I, IGF-II and belongs to the large class of receptor tyrosine kinase. [5] Metabolically, the insulin receptor plays a key role in the regulation of glucose homeostasis; a functional process that under degenerate conditions may result in a range of clinical manifestations including diabetes and cancer.