Synthesis and intracellular transport of proteins in the exocrine pancreas of the frog (Rana esculenta)

Slot, Jan W.; Geuze, J. J.; Poort, C.

doi:10.1007/bf00221350

Cited by 28 publications

(22 citation statements)

References 35 publications

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“…Pulse-labeling experiments were performed under conditions previously reported (24). Fragments of fasted and fed tissue were incubated by immersion in 2 ml of incubation fluid in conical flasks, which were gently shaken.…”

Section: In Vitro Incubationmentioning

confidence: 99%

“…After different time intervals, the incubation was stopped by washing the tissue in ice-cold medium containing 75 mM nonlabeled leucine. The tissue was homogenized, and trichloroacetic acid (TCA)insoluble radioactivity was measured and expressed per microgram DNA (23).…”

Section: In Vitro Incubationmentioning

confidence: 99%

“…For electrophoresis, tissue fragments were incubated for 30 min by immersion in a medium containing a ~Camino acid mixture (80 p, Ci/ml medium, sp act 45 mCi/ milliatom of carbon, Radiochemical Centre). Unlabeled amino acids were not added except for those that were either not present or were present in relatively low concentration in the 14C-mixture, so that the concentration of all essential amino acids varied between 10 and 20% of the concentration usually added to the incubation medium (24).…”

Section: In Vitro Incubationmentioning

confidence: 99%

“…Details of this procedure are given elsewhere (23,24). After incubation, tissue fragments were fixed in 1% OsO4 (pH 7.4), and embedded in Epon 812.…”

Section: Electron Microscope Autoradiographymentioning

confidence: 99%

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Effect of fasting and feeding on synthesis and intracellular transport of proteins in the frog exocrine pancreas.

Slot¹,

Strous²,

Geuze³

1979

The Journal of Cell Biology

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Frog exocrine pancreatic tissue was studied in vitro under conditions which maintain the differences between tissues from fasted and fed animals. Sodium dodecyl sulfate (SDS) gel electrophoresis after labeling with [14C]amino acids showed that feeding stimulated the synthesis of secretory proteins to the same relative degree as the overall protein synthesis.The intracellular transport of secretory proteins was studied by electron microscope autoradiography after pulse-labeling with [ZH]leucine. It was found that the transport route is similar under both feeding conditions. After their synthesis in the rough endoplasmic reticulum (RER), the proteins move through the peripheral elements and cisternae of the Golgi system into the condensing vacuoles. The velocity of the transport increases considerably after feeding. When frogs are fasted, the release of labeled proteins from the RER takes >90 min, whereas after feeding, this happens within 30 min. Comparable differences were observed for transport through the Golgi system. The apparent differences between the frog and mammalian pancreas in the regulation of synthesis, intracellular transport, and secretion of proteins are discussed. KEY WORDS frog exocrine pancreas feeding protein synthesis intraceUular transportIn serous cells, secretory proteins are synthesized at the membrane-bound ribosomes of the rough endoplasmic reticulum (RER) and are subsequently transported along the well-known RERGolgi system-secretory granule route. It has been shown that protein transport in these organelles is not affected by treatments that influence protein synthesis (3,7,18) or secretion (10,20,21), and that it depends on a continuous supply of energy (4,8). This suggests that protein transport is not a passive process driven by the pressure of newly synthesized protein molecules.The effect of feeding on the velocity of intracellular transport of secretory proteins has not yet been studied in pancreatic tissue. In rats, synthesis and secretion have been reported to be affected only moderately by feeding (15). On the other hand, synthesis and secretion of proteins strongly increase in the frog pancreas after feeding (22,25). Therefore, the exocrine cell of the frog pancreas seemed suitable for studying the process of intracellular transport in relation to different levels of synthesis and secretion.In this article, we describe the transport of in 708J. CELL BIOLOGY 9 The Rockefeller University Press -0021-9525/79/03/0708-0751.00

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Section: In Vitro Incubationmentioning

confidence: 99%

Section: In Vitro Incubationmentioning

confidence: 99%

Section: In Vitro Incubationmentioning

confidence: 99%

“…Details of this procedure are given elsewhere (23,24). After incubation, tissue fragments were fixed in 1% OsO4 (pH 7.4), and embedded in Epon 812.…”

Section: Electron Microscope Autoradiographymentioning

confidence: 99%

See 2 more Smart Citations

Effect of fasting and feeding on synthesis and intracellular transport of proteins in the frog exocrine pancreas.

Slot¹,

Strous²,

Geuze³

1979

The Journal of Cell Biology

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“…Clusters of PE are found in areas, the transitional areas (TA), which are largely surrounded by TE. The occurrence of protuberances at the concave TE membrane suggest the formation of PE, which provide for the vesicular transport of newly synthesized secretory proteins between RER and Golgi stack (Jamieson and Palade, 1967;Slot et al, 1976Slot et al, , 1983. In other cell types structures comparable with the PE in pancreatic cells, have been named pre-Golgi vacuoles (Saraste and Kuismanen, 1984;Saraste et al, 1987), salvage compartment (Warren, 1987), budding compartment (Tooze et al, 1988), intermediate compartment (Schweizer et al, 1988(Schweizer et al, , 1991, and cis-Golgi network (Hsu et al, 1991;Pelham, 1991;Rothman and Orci, 1992).…”

mentioning

confidence: 99%

Beta-COP localizes mainly to the cis-Golgi side in exocrine pancreas.

Oprins

Duden

Kreis

et al. 1993

The Journal of Cell Biology

191

107

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Abstract. We examined the distribution of the nonclathrin-coated vesicle-associated coat protein t-COP in rat exocrine pancreatic cells by immunogold cytochemistry. Labeling for/~-COP was found in the Golgi region (48%) where it was associated with vesicles and buds of "o50 nm, showing a characteristic "ol0-nm-thick coat. The other half of the label was present in the cytoplasm, not associated with visible coats or membranes, with a minor fraction present on small clusters of tubules and vesicles. Clathrin-coated vesicles were typically located at the trans-side of the Golgi complex, and showed a thicker coat of ,o18 nm. Of the total t-COP labeling over the Golgi region, 68% occurred on the cis-side, 6% on the cisternae, 17% on the rims of the cisternae, and only 9% on the trans-side. For clathrin these figures were 16, 2, 4, and 78%, respectively. At the cis-Golgi side/~-COP was present in transitional areas (TA), on so-called peripheral elements (PE), consisting of tubules and vesicles located between the cup-shaped transitional elements (TE) of the RER and the cis-most Golgi cisternae. Label for Sec23p was also present in TA but was located closer to the TE, while H-COP labeled PE were located near the cis-Golgi cisternae. Upon energy depletion, Golgi associated/S-COP was almost exclusively (86%) in spherical aggregates of 200-500 nm in diameter, whereas the cis-side (6%), the cisternae (1%), the rims (4%) and trans-side (3%) of the Golgi complex, were barely labeled; 50% of the total label remained in the cytoplasm. The aggregates were predominantly located at the cis-side of the Golgi stack, next to, but distinct from the Sec23p positive TA, that were devoid of/S-COP and had only a few recognizable vesicles left. Incubation with aluminum fluoride resulted in fragmentation of the Golgi complex into large clusters of/3-COP positive vesicles, while 50% of the label remained in the cytoplasm, as in control cells. After 10 min of Brefeldin A treatment 91% of/3-COP was cytoplasmic and only 7% associated with membranes of the Golgi complex. The total label for/3-COP over exocrine cells remained unchanged during the incubation with either of the drugs, indicating that the drugs induce reaUocation of t-COP. Our data suggest that/3-COP plays a role in membrane transport at the cis-side of the Golgi complex.

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Formation of secretion granules in the Golgi apparatus of pancreatic acinar cells of the rat

1988

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The three-dimensional structure of the Golgi apparatus and its components has been analyzed in sections of pancreatic acinar cells by using stereopairs of electron microscope photographs. Pancreatic tissue fixed in glutaraldehyde was postfixed in reduced osmium, and the sections were stained with lead citrate. Tissues were also treated to demonstrate phosphatase activity (i.e., nicotinamide adenine dinucleotide phosphatase, NADPase; thiamine pyrophosphatase, TPPase; cytidine monophosphatase, CMPase). The following stacked components were observed along the branching, anastomotic, continuous, ribbonlike Golgi apparatus. 1) On the cis-face of the Golgi stack there was a tubular membranous network known to be osmiophilic and referred to as the cis-osmiophilic tubular network or cis-element. 2) A first, poorly fenestrated saccule, unreactive for the phosphatases tested, was slightly distended in places and contained a fluffy granulofilamentous material. 3) The subjacent three or four saccules, reactive for NADPase and/or TPPase, showed dilated portions containing a granulofilamentous secretory material similar to that filling the rest of the saccule. They also showed nondilated portions perforated with large fenestrations, some of which were in register and formed wells containing 80-nm vesicles. The dilated portions of these saccules were present at random along the length of the saccules and were not located exclusively at their edges. 4) The remaining one or two elements of the stack, CMPase positive, showed dilated spheroidal portions or prosecretory granules containing a homogeneous secretory material and flattened fenestrated regions free of secretory material and having the appearance of networks of narrow membranous tubules. 5) Lastly on the trans-aspect of the stack there were detached prosecretory granules reactive for CMPase and surrounded by a corona of small vesicles, and smooth-surfaced spherical CMPase-negative granules having a denser content that were identified as fully formed secretion granules; there were also occasional free trans-tubular networks strongly reactive for CMPase that appeared to undergo fragmentation and numerous small vesicles free from acid-phosphatase activity. These various images were interpreted as indicating that prosecretory granules formed in relation to two or three fenestrated saccules on the trans-side of the stack. Such granules, following their detachment from the trans-face of the stack, their separation from trans-tubular networks, and condensation of their content, yielded mature secretion granules.

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Synthesis and intracellular transport of proteins in the exocrine pancreas of the frog (Rana esculenta)

Cited by 28 publications

References 35 publications

Effect of fasting and feeding on synthesis and intracellular transport of proteins in the frog exocrine pancreas.

Effect of fasting and feeding on synthesis and intracellular transport of proteins in the frog exocrine pancreas.

Beta-COP localizes mainly to the cis-Golgi side in exocrine pancreas.

Formation of secretion granules in the Golgi apparatus of pancreatic acinar cells of the rat

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