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This aquaporin is regulated in two ways by the peptide hormone vasopressin: short-term regulation (minutes) through trafficking of AQP2 vesicles to the apical region where they fuse with the apical plasma membrane; long-term regulation (days) through an increase in AQP2 gene expression. This aquaporin is also regulated by food intake.
Endocrinology (from endocrine + -ology) is a branch of biology and medicine dealing with the endocrine system, its diseases, and its specific secretions known as hormones.It is also concerned with the integration of developmental events proliferation, growth, and differentiation, and the psychological or behavioral activities of metabolism, growth and development, tissue function, sleep ...
The aromatic/arginine or "ar/R" selectivity filter is a cluster of amino acids that help bind to water molecules and exclude other molecules that may try to enter the pore. It is the mechanism by which the aquaporin is able to selectively bind water molecules and so to allow them through, and to prevent other molecules from entering.
An important feature is the presence of zinc atoms (Zn 2+) on the axis of symmetry, which are surrounded by three water molecules and three histidine residues at position B10. [17] [46] The hexamer is an inactive form with long-term stability, which serves as a way to keep the highly reactive insulin protected, yet readily available.
Hydrophilic molecules: water-soluble molecules, such as cAMP, cGMP, IP 3, and Ca 2+, that are located within the cytosol. Gases: nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H 2 S) which can diffuse both through cytosol and across cellular membranes. These intracellular messengers have some properties in common: [citation needed]
The two factors work together to return the plasma osmolality to its normal levels. ADH binds to principal cells in the collecting duct that translocate aquaporins to the membrane, allowing water to leave the normally impermeable membrane and be reabsorbed into the body by the vasa recta, thus increasing the plasma volume of the body.
To release active hormones quickly into the circulation, hormone biosynthetic cells may produce and store biologically inactive hormones in the form of pre-or prohormones. These can then be quickly converted into their active hormone form in response to a particular stimulus. [34] Eicosanoids are considered to act as local hormones. They are ...
Hormones can be amino acid complexes, steroids, eicosanoids, leukotrienes, or prostaglandins. [3] The endocrine system is contrasted both to exocrine glands, which secrete hormones to the outside of the body, and to the system known as paracrine signalling between cells over a relatively short distance.