Expression of proteolytic enzymes during Dictyostelium discoideum spore germination |
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Authors: | Dennis P. Jackson David A. Cotter |
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Affiliation: | (1) Biology Department, University of Windsor, N9B 3P4 Windsor, Ontario, Canada;(2) Present address: Dept. of Immunology and Microbiology, University of Western Ontario, London, Ontario, Canada |
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Abstract: | The specific activity of cathepsin B-like, cathepsin D-like, and leucine aminopeptidase enzymes was measured in dormant, aging, and germinating spores of wild-type and mutant Dictyostelium discoideum.The activity of leucine aminopeptidase was relatively constant during spore aging and spore germination. The level of cathepsin D-like activity was highest in young dormant spores but decreased during germination or aging.The level of cathepsin B-like activity remained constant in wild-type spores which were aged for 13 days. The dormant spores of spontaneous germination mutants initially contained low levels of cathepsin B-like activity which increased during aging. Thus, there was no correlation between the level of endogenous cathepsin B activity and the ability to be autoactivated or heat-activated. The level of cathepsin B-like activity does not have a role in the generation of energy for the swelling stage of germination. Finally, the combined level of endogenous and exogenous cathepsin B activity increased more than 20-fold during the emergence of myxamoebae suggesting that the enzyme(s) may play a role at this development stage of germination. |
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Keywords: | Dictyostelium discoideum Spores Germination Cathepsin B Cathepsin D Leucine aminopeptidase |
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