The developmental regulation of phosphatidylinositol kinase in Dictyostelium discoideum |
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| Affiliation: | 1. Metabolisme, Nutricion y Hormonas, Institute de Investigaciones Biomedicas del CSIC, Fundacion Jimenez Diaz, Avenida Reyes Catolicos 2, 28040 Madrid, Spain;2. Cell Biology and Morphogenesis Unit, Zoological Laboratory, University of Leiden, Kaiserstraat 63, NL-2311 GP Leiden, The Netherlands |
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| Abstract: | Phosphatidylinositol kinase was examined in Dictyostelium discoideum since this organism offers molecular and genetic advantages to study the role of phosphatidylinositol metabolism during cell growth and development. D. discoideum homogenates phosphorylated phosphatidylinositol to form phosphatidylinositol 4-phosphate in a reaction which was found to be linear with time and cell concentration. Optimal activity was obtained in the presence of 1 mM MgCl2 and pH 7.6 and has an apparent Km for ATP of about 250 μM. Changes in phosphatidylinositol kinase were examined during D. discoideum development. Activity increased about 2-fold, 4 h after removal of the food source, to decline to almost no activity at late aggregation. During slug formation the activity increased about 15-fold and remained constant during further development. These results suggest a role for D. discoideum phosphatidylinositol kinase during development. |
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