Thioredoxin, despite its function as an intracellular disulfide reducing enzyme and its lack of a signal sequence, has been found to play some roles extracellularly. Here we show that thioredoxin is actively secreted by a variety of normal and transformed cells, including fibroblasts, airway epithelial cells, and activated B and T lymphocytes. Neither brefeldin A nor dinitrophenol, two drugs that block transport through the exocytic pathway, inhibit secretion of thioredoxin, indicating that the latter does not follow the classical ER-Golgi route. The secretory mechanism for thioredoxin shares several features with the alternative pathway described for interleukin- 1β, such as the potentiating effect on secretion of several unrelated drugs and the sensitivity to methylamine. However, unlike interleukin-1β, thioredoxin is not detected in membrane-bound compartments of secreting cells. In addition, when COS7 are transfected with plasmids encoding pro- interleukin-1β or thioredoxin, only the latter is detectable extracellularly.
|Number of pages||4|
|Journal||Journal of Biological Chemistry|
|Publication status||Published - 1992|
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