Intracellular transport of sulfated macromolecules in parotid acinar cells

Berg, Norton B.; Austin, B.P.

doi:10.1007/bf00226660

Cited by 28 publications

(10 citation statements)

References 25 publications

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“…However, data are still lacking on the dry mass fraction of the rat parotid gland secretary granule per se. The present S finding in secretary granules is consistent with the known incorporation of S into secretary macromolecules in the golgi region and their subsequent transport into secretary granules (Reggio & Palade, 1975;Berg & Austin, 1976). The high P levels in cytoplasm and nuclei relative to secretary granules can probably be attributed to high RNA (cytoplasmic and nuclear) and DNA (nuclear) levels, the former probably being associated with secretary protein synthesis (Palade, 1975;Wallach, 1982).…”

Section: Concentration Differences In Organelles Of Resting Glandssupporting

confidence: 87%

Changes in elemental concentrations of rat parotid acinar cells following pilocarpine stimulation.

Izutsu¹,

Johnson²

1986

The Journal of Physiology

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SUMMARY1. Quantitative electron microprobe analysis was used to measure elemental dry weight concentrations in cytoplasm, secretary granules and nuclei of resting and pilocarpine-stimulated rat parotid gland acinar cells.2. Secretory granules in resting cells had lower concentrations of Na, Mg, P, Cl and K, and higher concentrations of S and Ca than cytoplasm or nuclei. Nuclei in resting cells had lower S and higher K concentrations than cytoplasm.3. Three major pilocarpine-related changes were found: (i) cytoplasmic dry weight concentrations of Na and Ca increased and the concentration of K decreased, (ii) the nuclear concentration of Na increased while that of K decreased and (iii) the concentrations of Na and Cl increased in secretary granules.4. These results indicate that the nuclear, and cytoplasmic compartments have different mechanisms for regulating their elemental concentrations relative to the secretary granules.5. The present results are largely consistent with X-ray microanalysis results from the pilocarpine-stimulated dog submandibular gland.

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Section: Concentration Differences In Organelles Of Resting Glandssupporting

confidence: 87%

Changes in elemental concentrations of rat parotid acinar cells following pilocarpine stimulation.

Izutsu¹,

Johnson²

1986

The Journal of Physiology

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“…Hence, the very small amount of sulfated polyanions encountered in the Golgi complex may modify protein-to-protein interactions within the condensing vacuoles to a point at which aggregate formation becomes effective in the concentration process. Thi~ process may be of broad significance because sulfated compounds have been found in many secretory cells (24,2,6). Moreover, secretory cells appear to use a variety of ionic interactions in the concentration process (stereospecific interactions, metal complexing, etc.…”

Section: Discussionmentioning

confidence: 99%

Ionic interactions between bovine chymotrypsinogen A and chondroitin sulfate A.B.C.. A possible model for molecular aggregation in zymogen granules.

Reggio¹,

Dagorn²

1978

The Journal of Cell Biology

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The formation of large aggregates by ionic interactions between acidic glucosaminoglycans and cationic secretory proteins has been proposed as one of the critical steps in the concentration process in the condensing vacuoles of secretory cells. In this paper, this hypothesis was tested by studies on the interactions between bovine chymotrypsinogen A and chondroitin sulfate as a simplified model. Small amounts of chondroitin sulfate were found able to induce chymotrypsinogen precipitation. Like zymogen granules, the resulting aggregates were moderately sensitive to ionic strength and insensitive to osmolality. Moreover, their pH dependence was similar to that of isolated zymogen granules. When sulfated glucosaminoglycans isolated from the zymogen granules of the guinea pig pancreas were used instead of chondroitin sulfate, the same kind of interactions with chymotrypsinogen were obtained. Our data support the hypothesis that the strong ionic inteFactions between those sulfated glucosaminoglycans and cationic proteins could be responsible for the concentration process.KEY WORDS chymotrypsinogen A 9 chondroitin sulfate glucosaminoglycans molecular aggregation zymogen granule condensation turbidity A sulfated macromolecular fraction has recently been isolated from the zymogen granules of the guinea pig pancreas (17, 18). Preliminary results indicate that this fraction is composed of acidic glucosaminoglycans, principally heparan sulfate and chondroitin sulfate (18). Such compounds have been implicated in the process by which pancreatic acinar cells concentrate their secretory proteins in the condensing vacuoles of the Golgi complex (23,16,9). The formation of large aggregates by ionic interactions between those polyanions and cationic secretory proteins could reduce the osmotic activity within the vacuoles and lead to concentration of their content by water loss. In this paper, this hypothesis was tested by studies on the interactions between bovine chymotrypsinogen A (ChTg) and chondroitin sulfate (Ch-SO4) as a simplified model. The results indicate that the ionic interactions of these compounds are strong enough to induce coprecipitation. Sulfated polyanions isolated from the zymogen granules of the guinea pig pancreas were found to interact with bovine ChTg in a manner comparable to that of Ch-SO4. MATERIALS AND METHODSBovine chymotrypsinogen A (Worthington Biochemical Corp., Freehold, N.J.) dissolved (1 mg/ml) in 2 mM Tris maleate buffer, pH 6, was mixed with solutions of J. CELL BIOLOGY 9 The Rockefeller University Press -0021-9525/78/0901-095151.00 951 on

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“…Sulfated macromolecules are widely distributed products of regulated secretory cells and received early attention as macromolecules that might promote the storage of proteins and biogenic amines through electrostatic interactions (Berg and Austin, 1976;Reggio and Palade, 1978;Uvnas and Aborg, 1983). Subsequently, different types of studies have provided findings that are consistent with this notion; however, it is striking that among these systems there is no generic sulfated molecule but instead a variety of different precursors that undergo sulfation in potential relation to the storage process.…”

Section: Post-translational Modifications In Sortingmentioning

confidence: 99%

Intracellular Transport and Secretion of Salivary Proteins

Castle

1998

Critical Reviews in Oral Biology & Medicine

109

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Intracellular transport and secretion of salivary proteins are major activities of salivary acinar cells. While the major intracellular pathway followed by salivary proteins following their synthesis has been described previously, there is only limited understanding of how this process is regulated at the molecular level. Studies of salivary proteins, especially proline-rich proteins, expressed in an endocrine cell line have begun to provide insight regarding intermolecular interactions during transport and the role played by structural signals during intracellular sorting. Analysis of the secretion of newly synthesized salivary proteins in parotid tissue has shown that there are multiple pathways of discharge from acinar cells. While granule exocytosis is the major pathway, at least two other pathways that export salivary proteins have been found to originate from maturing secretion granules. These pathways may contribute to other acinar cell functions, including secretion of proteins in the absence of acute stimulation and support of the secretory process for fluid and electrolytes.

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Intracellular transport of sulfated macromolecules in parotid acinar cells

Cited by 28 publications

References 25 publications

Changes in elemental concentrations of rat parotid acinar cells following pilocarpine stimulation.

Changes in elemental concentrations of rat parotid acinar cells following pilocarpine stimulation.

Ionic interactions between bovine chymotrypsinogen A and chondroitin sulfate A.B.C.. A possible model for molecular aggregation in zymogen granules.

Intracellular Transport and Secretion of Salivary Proteins

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