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The production of a secretory protein starts like any other protein. The mRNA is produced and transported to the cytosol where it interacts with a free cytosolic ribosome . The part that is produced first, the N-terminal, contains a signal sequence consisting of 6 to 12 amino acids with hydrophobic side chains.
Increased cAMP level results in increased protein kinase A. Protein kinase A phosphorylates proteins involved in the transport of H + /K +-ATPase from the cytoplasm to the cell membrane. This causes resorption of K + ions and secretion of H + ions. The pH of the secreted fluid can fall by 0.8.
H + is pumped into the stomach by exchanging it with K +. This process also requires ATP as a source of energy; however, Cl − then follows the positive charge in the H + through an open apical channel protein. HCO 3 − secretion occurs to neutralize the acid secretions that make their way into the duodenum of the small intestine.
The secretion is a complex and relatively energetically expensive process. Parietal cells contain an extensive secretory network (called canaliculi) from which the hydrochloric acid is secreted into the lumen of the stomach. The pH of gastric acid is 1.5 to 3.5 in the human stomach lumen, a level maintained by the proton pump H + /K + ATPase. [1]
In a channel transport system, several proteins form a contiguous channel traversing the inner and outer membranes of the bacteria. It is a simple system, which consists of only three protein subunits: the ABC protein , membrane fusion protein (MFP), and outer membrane protein .
Pancreatic secretion is an aqueous solution of bicarbonate originating from the duct cells and enzymes originating from the acinar cells. The bicarbonate assists in neutralising the low pH of the chyme coming from the stomach, while the enzymes assist in the breakdown of the proteins, lipids and carbohydrates for further processing and ...
As these two chemicals would damage the stomach wall, mucus is secreted by innumerable gastric glands in the stomach, to provide a slimy protective layer against the damaging effects of the chemicals on the inner layers of the stomach. At the same time that protein is being digested, mechanical churning occurs through the action of peristalsis ...
Affects gut motility; increases jejunal and ileal fluid secretion Pancreatic polypeptide: Pancreas: Inhibits pancreatic and biliary secretion Peptide YY: Colon: Inhibits food intake Somatostatin: Stomach, pancreas: Inhibits secretion and action of many hormones Substance P: Enteric nerves: Unclear Trefoil peptides: Stomach, intestine: Mucosal ...