title: Membrane sites regulating developmental gene expression in Dictyostelium discoideum.
abstract: Postaggregative gene expression in Dictyostelium discoideum requires cell contact. Polyspecific monovalent antibodies (Fab) prepared from sera raised against membranes of aggregation- and postaggregation-stage cells were used to probe the cell interactions that induce rapid postaggregative synthesis of UDP-glucose pyrophosphorylase. When cells of strain V12M2 were dissociated after 8 hr of development and replated in the presence of immune Fab, both reaggregation and pyrophosphorylase synthesis were blocked. Fab neutralized by incubation with EDTA-high salt extracts of cells developed for 3 hr blocked pyrophosphorylase synthesis but not reaggregation. Therefore, some cell-surface components that regulate pyrophosphorylase synthesis (called E sites) are antigenically distinct from those required for reaggregation. The Fab provides a means to assay E sites during their purification. Addition of 10(-3) M cyclic AMP or cyclic GMP enabled the cells to bypass the blocking of E sites by Fab; pyrophosphorylase was synthesized in the absence of reaggregation. We hypothesize that E sites function by raising the level of intracellular cyclic AMP.
mesh_terms: D002450:Cell Communication; D002462:Cell Membrane / Q000378:metabolism*; D000242:Cyclic AMP / Q000494:pharmacology; D006152:Cyclic GMP / Q000494:pharmacology; D004023:Dictyostelium / Q000235:genetics* / Q000254:growth & development; D004492:Edetic Acid / Q000494:pharmacology; D004790:Enzyme Induction; D005786:Gene Expression Regulation; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase / Q000096:biosynthesis
chemical_list: D007140:Immunoglobulin Fab Fragments; D004492:Edetic Acid; D000242:Cyclic AMP; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase; D006152:Cyclic GMP