The Journal of Cell Biology, Vol 72, 406-423, Copyright © 1977 by The Rockefeller University Press

ARTICLES

Immunocytochemical localization of secretory proteins in bovine pancreatic exocrine cells

JP Kraehenbuhl, L Racine and JD Jamieson

The bovine exocrine pancreatic cell produces a variety of enzymes and proenzymes for export. Biochemical studies by Greene L.J., C.H. Hirs, and G.E. Palade (J. Biol. Chem. 1963. 238:2054) have shown that the mass proportions of several of these proteins in resting pancreatic juice and zymogen granule fractions are identical. In this study we have used immunocytochemical techniques at the electron microscope level to determine whether regional differences exist in the bovine gland with regard to production of individual secretory proteins and whether specialization of product handling occurs at the subcellular level. The technique used is a modification of one previously reported (McLean, J.D., and S.J. Singer. 1970. Proc. Natl. Acad. Sci U.S.A. 69:1771) in which immunocytochemical reagents are applied to thin sections of bovine serum albumin-imbedded tissue and zymogen granule fractions. A double antibody technique was used in which the first step consisted of rabbit F(ab')2 antibovine secretory protein and the detection step consisted of sheep (F(ab')2 antirabbit F(ab')2 conjugated to ferritin. The results showed that all exocrine cells in the gland, and all zymogen granules and Golgi cisternae in each cell, were qualitatively alike with regard to their content of secretory proteins examined (trypsinogen, chymotrypsinogen A, carboxypeptidase A, RNase, and DNase). The data suggest that these secretory proteins are transported through the cisternae of the Golgi complex where they are intermixed before copackaging in zymogen granules; passage through the Golgi complex is apparently obligatory for these (and likely all) secretory proteins, and is independent of extent of glycosylation, e.g., trypsinogen, a nonglycoprotein vs. DNase, a glycoprotein.
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• Griffiths, G, Simons, K (1986). The trans Golgi network: sorting at the exit site of the Golgi complex. Science 234: 438-443 [Abstract]  
• Mroz, E., Lechene, C (1986). Pancreatic zymogen granules differ markedly in protein composition. Science 232: 871-873 [Abstract]  
• Adelson, J., Miller, P. (1985). Pancreatic secretion by nonparallel exocytosis: potential resolution of a long controversy. Science 228: 993-996 [Abstract]  
• Reddy, J., Rao, M. (1977). Transplantable pancreatic carcinoma of the rat. Science 198: 78-80 [Abstract]  

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