Zymogen granules

RC Delisle, U Hopfer. (1986). Electrolyte permeabilities of pancreatic zymogen granules Implications for pancreatic secretion. Am J Physiol 250 G489-G496. 

KW Gasser, J DiDomineco, UH Hopfer. (1988). Secretagogues activate chloride transport pathways in pancreatic zymogen granules. Am J Physiol 254 G93-G99. 

Scheffer, R. C. T., Poort, C. and Slot, J. W. 1980. Fate of the major zymogen granule membrane-associated glycoproteins from rat pancreas. A biochemical and immunocytochemical study. Eur. J. Cell Biol 23, 122-128. 

On these observations is based the Palade and Siekevitz theory according to which pancreatic enzymes are synthesized in ribosomes, segregated into exportable and nonexportable enzymes in the reticulum cisternae and the Golgi apparatus. The exportable enzymes are then stored in zymogen granules until the next stimulation induces them to pass into the juice. It will be of interest to see to what extent this theory can be confirmed by chemical techniques. 

Pancreatic juice collected over an extended period of time by a permanent fistula may be considered an ideal material for studying the net synthesis of a series of well-defined proteins. As soon as radioactive proteins are present in zymogen granules they may appear in the juice after a certain delay, which depends upon the conditions of the next stimulation. When rats in which a continuous flow of juice is promoted by secretin or... 

Sulfuric acid, phosphate, and sucrose extracts of mouse and beef pancreas have also been compared chromatographically on Amberlite IRC-50 (154). For both species, the sulfuric acid extracts give two peaks which correspond to ribonucleases A and B. When prepared from supernatant free of zymogen granules and microsomes, phosphate and sucrose preparations give a third peak, (10-15 % of the total activity in the case of mouse 1 % in the case of beef) which can be converted into the previous ones by acid treatment. This treatment induces a two- to three-fold increase in activity and the dissociation of the acidic compound already referred to above. The chemical structure of mouse ribonuclease(s) is still unknown. 

Braun JEA, Fritz BA, Wong SME, Lowe AW (1994) Identification of a vesicle-associated membrane protein (VAMP-like) membrane protein in zymogen granules of the rat exocryne pancreas. In J. Biol. Chem. 269 5328-35 Brennwald P, Kearns B, Champion K, Keranen S, Bankaitis V, Novick P (1994) Sec9 is a SNAP-25-like component of a yeast SNARE complex that may be the effector of Sec4 function in excytosis. In Cell 79 245—58 Broadie K, Prokop A, Bellen HJ, O Kane C, Schulze KL, Sweeney ST (1995) Syntaxin and synaptobrevin function downstream of vesicle docking in Drosophila. In Neuron 15 663-73... 

Gaisano HY, Sheu L, Foskett JK et al. (1994) Tetanus toxin light chain cleaves a vesicle-associated membrane protein (VAMP) isiform 2 in rat pancreatic zymogen granules and inhibits enzyme secretion. J. Biol. Chem. 269 17062-6. 

Native HPL is a glycosylated 50 kDa protein which is synthesized by acinar ceUs of the pancreas (Fig. 10.2). In the cell, this hpase is located with many other enzymes into the zymogen granules, and is then secreted through the pancreatic duct into the intestinal lumen together with the bile. Secretion of HPL can be stimulated by intestinal hormones such as CCK-PZ and secretin (Zieve et al., 1966a,b). Lipolysis products (FFAs) are known to stimulate the HPL secretion indirectly through the CCK action (Hildebrand et al., 1998). HPL secretion is drasti-... 

Fig- 10.2 Immunocytolocalization of HPL in the zymogen granules of pancreatic acinar cells. Zymogen granules are specifically... 

Fig. 3. An apoptotic pancreatic acinar cell from a rat treated with 1-cyano-2-hydroxy-3-butene. The cell has a rounded morphology and has lost all but a few of its zymogen granules ( ). There is early condensation of nuclear chromatin (small arrows) around the margins of the nuclear envelope and the nucleolus (nu) is partially segregated from the chromatin. Most mitochondria (M) are normal in morphology, although one swollen one (large arrow) with microhemiation is present. Bar = 5 pm.

Pancreatic zymogen granule protein GP2 Paraoxonase parathyroid hormone Parathyroid hormone-related protein PASP... 

FIGURE 17.1 Microscopic appearance of the normal rat pancreas. An islet of endocrine cells is surrounded by acinar cells of the exocrine pancreas in a normal rat. A, arteriole AC, acinar cells D, ductule 1, islet V, venule ZG, zymogen granules. (H E stain original magnification 200x) (See insert for color representation of the figure.)... 

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