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S J Quirk

Publications and source records attributed to S J Quirk.

22 records · Page 2Linked to original sources
PubMed1976

Changes in the distribution of intramembranous particles in hen erythrocytes during cell fusion induced by the bivalent-cation ionophore A23187.

Incubation of hen erythrocytes with Ca2+ and the bivalent-cation ionophore A23187 induced slight cell fusion in 1 h at 37 degrees C, and extensive fusion during a subsequent 15 min at 47 degrees C. Redistributions of intramembranous particles were observed, possibly involving interactions between Ca2+ and phospholipids, which are discussed in relation to molecular mechanimss of cell fusion.

Animals↗
PubMed1973

Studies on the turnover of protein and glycoprotein components in rabbit kidney brush borders.

The kinetics of incorporation of [(3)H]lysine and [(14)C]glucosamine into kidney brush borders were studied in vivo. The patterns of incorporation and loss of radioactivity from the brush borders were similar for both radioactively labelled precursors. Maximal labelling occurred 15-20h after injection of the precursors, and then the radioactivity declined rapidly until 50h. The radioactivity of brush borders then remained constant until 120h and thereafter declined slowly. These results are interpreted as indicating that two processes contribute to the turnover of brush-border components, pinocytosis and a slower turnover of the components of the microvilli. Studies of the distribution of radioactivity among glycoprotein components of the brush borders, separated by polyacrylamide-gel electrophoresis, indicated that the membrane components turned over in unison.

Animals↗
PubMed1972

Isolation and characterization of rabbit kidney brush borders.

1. Brush borders were isolated from rabbit kidney-cortex homogenates by rate-zonal centrifugation through a sucrose density gradient in a B-XIV zonal rotor, followed by differential centrifugation. 2. The method of preparation gave brush borders of high purity with a reasonable yield. The morphological appearance supported the evidence from enzymic and chemical investigations, that the brush borders were only slightly contaminated with endoplasmic reticulum, mitochondria, lysosomes and nuclei. 3. The molar ratio of cholesterol to phospholipid lay within the range found in other plasma membranes, but the carbohydrate content was double that found in liver plasma membranes. 4. Alkaline phosphatase, maltase, trehalase and aminopeptidase were major enzymic constituents of the brush borders, and had an approximately equal yield and enrichment, but none of these enzymes fulfilled the criteria for marker enzymes. 5. Mg(2+)-dependent and Na(+),K(+)-dependent adenosine triphosphatases, although found in brush borders, had low yields and low enrichments.

Adenosine Triphosphatases↗