To clearly identify cells and organelles containing the common precursor (31,000 dalton) for both adrenocorticotropin (ACTH) and beta-lipotropin (beta-LPH), an immunohistochemical localization of a fragment (16,000 dalton) of the precursor that is not common to beta-LPH and ACTH was conducted in rat and human pituitary glands. With the help of specific antibodies that do not cross-react with beta-LPH and ACTH, the 16,000-dalton fragment was localized in the cells that also produce ACTH and beta-LPH in both the pars distalis and pars intermedia of the rat pituitary. At the electron microscope level, the secretory granules that contain ACTH were also stained for 16,000-dalton fragment. In the human pituitary, the 16,000-dalton fragment was also observed in all the secretory granules of lipocorticotrophs. These results suggest that, after enzymatic cleavage, fragment(s) of the common precursor and/or the whole common precursor remain packaged within the secretory granules with peptides of known activity.
Localization of a 16,000-dalton fragment of the common precursor of adrenocorticotropin and beta-lipotropin in the rat and human pituitary gland.
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J Guy, R Leclerc, G Pelletier; Localization of a 16,000-dalton fragment of the common precursor of adrenocorticotropin and beta-lipotropin in the rat and human pituitary gland.. J Cell Biol 1 September 1980; 86 (3): 825–830. doi: https://doi.org/10.1083/jcb.86.3.825
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