[The immunohistochemical demonstration of the Thiol: proteindisulfid oxidoreductase (TPO) in pancreas and isolated Langerhans'islets. A light-, fluorescent- and electron microscopic study (author's transl)].

Thiole: Protein disulfide Oxidoreductase (E. C. 1.8.4.2) is capable of catalyzing thiole-disulfid exchange reactions and might have an important function in both protein biosynthesis and degradation. By using histochemical methods we were able to demonstrate the localization of this enzyme in the Langerhans'islets and in the acinus cells of rat pancreas. The reaction of the acinus cells, however, was much weaker than that of the islets. Electron microscopic experiments revealed the enzyme to be located in the outer membrane of the nucleus, in the membranes of the endoplasmic reticulum and B-cell granules, and in the plasmalemma also. All these structures are known to be involved in the insulin biosynthesis and secretion. There is a good correlation between morphological and biochemical findings. In acinus cells there are a few reaction in the outer nucleus membrane, the membranes of the endoplasmatic reticulum, and the plasmalemm.