Jeanne M. Richardson

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Radiolabel pulse-chase and subcellular fractionation procedures were used to analyze the transport, proteolytic processing, and sorting of two lysosomal enzymes in Dictyostelium discoideum cells treated with the weak bases ammonium chloride and chloroquine. Dictyostelium lacks detectable cation-independent mannose-6-phosphate receptors and represents an(More)
Lysosomal enzymes are initially synthesized as precursor polypeptides which are proteolytically cleaved to generate mature forms of the enzymatically active protein. The identification of the proteinases involved in this process and their intracellular location will be important initial steps in determining the role of proteolysis in the function and(More)
A mutant strain of Dictyostelium discoideum, HMW570, oversecretes several lysosomal enzyme activities during growth. Using a radiolabel pulse-chase protocol, we followed the synthesis and secretion of two of these enzymes, alpha-mannosidase and beta-glucosidase. A few hours into the chase period, HMW570 had secreted 95% of its radiolabeled alpha-mannosidase(More)
The developmentally regulated Dictyostelium discoideum lysosomal enzyme beta-glucosidase is synthesized as a membrane-associated glycosylated precursor polypeptide which undergoes at least two proteolytic cleavage events to generate a soluble mature lysosomally localized protein. To begin to analyze the mechanisms regulating the sorting of this protein and(More)
Human chronic myelogenous leukemia cell line K-562 expresses the bcr/c-abl fusion protein which is an active protein tyrosine kinase. Multiple tyrosine-phosphorylated proteins were detected in K-562 cells by immunoblotting with a high-affinity anti-phosphotyrosine antibody. When K-562 cells were induced with hemin to progress through the erythroid(More)
Dictyostelium discoideum is a useful system to study the biosynthesis of lysosomal enzymes because of the relative ease with which it can be manipulated genetically and biochemically. Previous studies have revealed that lysosomal enzymes are synthesized in vegetatively growing amoebae as glycosylated precursor polypeptides that are phosphorylated and(More)
Human chronic myelogenous leukemia cell line K-562 expresses the bcr/c-abl fusion protein which is an active protein tyrosine kinase. Mul tiple tyrosine-phosphorylated proteins were detected in K-S62 cells by ¡mmunoblotting with a high-affinity anti-phosphotyrosine antibody. When K-562 cells were induced with hemin to progress through the erythroid(More)
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