Abstract
Microsomes were isolated from the pancreas of starved and fed guinea pigs. In the first case, the gland was removed from animals starved for 48 hours; in the second, the pancreas was excised 1 hour after the beginning of a meal that ended a fast of 48 hours. These are referred to below as fed animals. In both cases the tissue was homogenized in 0.88 M sucrose and the microsomes obtained by centrifuging the mitochondrial supernatant at 105,000 g for 60 minutes. In starved animals the content of the endoplasmic reticulum of the exocrine cells and the content of the microsomes were found to be of low or moderate density. In fed guinea pigs the cavities of the reticulum frequently contained dense intracisternal granules and the microsomes were distinguished by a content of high density sometimes in the form of recognizable intracisternal granules. In starved animals, the microsomes were found to account for 5 to 20 per cent of the trypsin-activatable proteolytic activity and ribonuclease activity of the whole cell, whereas in fed animals they contained uniformly almost 30 per cent of these activities. In fed animals the dense, cohesive content of the microsomes (intracisternal granules) could be isolated by breaking up the microsomes with dilute (0.1 per cent) deoxycholate solutions and separating microsomal subfractions by differential centrifugation. The specific enzymatic activities of a heavy microsomal subfraction rich in intracisternal granules were almost equal to those of isolated purified zymogen granules. The ribonucleoprotein particles attached to the microsomal membranes could be isolated by the same technique and found also to exhibit some of the same enzymatic activities. Corresponding subfractions isolated from the microsomes of starved animals were considerably less active. The relevance of these findings for the synthesis and intracellular transport of protein in the exocrine cell of the pancreas is discussed.
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Selected References
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- ALLFREY V., DALY M. M., MIRSKY A. E. Synthesis of protein in the pancreas. II. The role of ribonucleoprotein in protein synthesis. J Gen Physiol. 1953 Nov 20;37(2):157–175. doi: 10.1085/jgp.37.2.157. [DOI] [PMC free article] [PubMed] [Google Scholar]
- DALY M. M., ALLFREY V. G., MIRSKY A. E. Synthesis of protein in the pancreas. III. Uptake of glycine-N15 by the trypsinogen and chymotrypsinogen of mouse pancreas. J Gen Physiol. 1955 Nov 20;39(2):207–210. doi: 10.1085/jgp.39.2.207. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HOKIN L. E. Isolation of the zymogen granules of dog pancreas and a study of their properties. Biochim Biophys Acta. 1955 Nov;18(3):379–388. doi: 10.1016/0006-3002(55)90101-3. [DOI] [PubMed] [Google Scholar]
- JUNQUEIRA L. C., HIRSCH G. C., ROTHSCHILD H. A. Glycine uptake by the proteins of the rat pancreatic juice. Biochem J. 1955 Oct;61(2):275–278. doi: 10.1042/bj0610275. [DOI] [PMC free article] [PubMed] [Google Scholar]
- PALADE G. E., SIEKEVITZ P. Liver microsomes; an integrated morphological and biochemical study. J Biophys Biochem Cytol. 1956 Mar 25;2(2):171–200. doi: 10.1083/jcb.2.2.171. [DOI] [PMC free article] [PubMed] [Google Scholar]
- PALADE G. E., SIEKEVITZ P. Pancreatic microsomes; an integrated morphological and biochemical study. J Biophys Biochem Cytol. 1956 Nov 25;2(6):671–690. doi: 10.1083/jcb.2.6.671. [DOI] [PMC free article] [PubMed] [Google Scholar]
- SCHNEIDER W. C., HOGEBOOM G. H. Intracellular distribution of enzymes. X. Desoxyribonuclease and ribonuclease. J Biol Chem. 1952 Sep;198(1):155–163. [PubMed] [Google Scholar]
- SCHUCHER R., HOKIN L. E. The synthesis and secretion of lipase and ribonuclease by pigeon pancreas slices. J Biol Chem. 1954 Oct;210(2):551–557. [PubMed] [Google Scholar]
- SIDRANSKY H., FARBER E. The effects of ethionine upon protein metabolism in the pancreas of rats. J Biol Chem. 1956 Mar;219(1):231–243. [PubMed] [Google Scholar]
- SIEKEVITZ P., PALADE G. E. A cytochemical study on the pancreas of the guinea pig. I. Isolation and enzymatic activities of cell fractions. J Biophys Biochem Cytol. 1958 Mar 25;4(2):203–218. doi: 10.1083/jcb.4.2.203. [DOI] [PMC free article] [PubMed] [Google Scholar]