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Immunoglobulin‐derived polypeptides enter the regulated secretory pathway in AtT‐20 cells
Author(s) -
Castle Anna M.,
Huang Amy Y.,
Castle J.David
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)01398-2
Subject(s) - secretion , secretory pathway , secretory protein , colocalization , microbiology and biotechnology , granule (geology) , intracellular , chemistry , biology , biochemistry , endoplasmic reticulum , golgi apparatus , paleontology
Constitutively secreted proteins have traditionally been believed to be excluded from the regulated secretory pathway. In this work we show that kappa light chain and Fc fragment, two markers of the constitutive pathway, are present in the regulated pathway in AtT‐20 cells. They colocalize with the endogenous hormone ACTH and they exhibit stimulus‐dependent secretion. The Fc fragment, which undergoes intracellular transport at the same rate as the ACTH precursor POMC, enters the forming secretory granules, however, it is partially lost during granule maturation. These observations show that classic constitutive secretory markers are not excluded from the regulated secretory pathway and that efficient sorting for regulated secretion occurs above a background of proteins which enter the granules without sorting.