title: Pyrophosphate-stimulated uptake of calcium into the germlings of Phytophthora infestans.
abstract: The uptake of 1 micrometer calcium into 6-h-old germination tubes of the fungus Phytophthora infestans follows Michaelis-Menten kinetics with a Km of 33 +/- 4 micrometer and a V of 0.3 nmol.min-1.(5 x 10(4) cells)-1. Uptake is inhibited by ruthenium red and lanthanum (both at 1 micrometer) and by the proton conductors 2,4-dinitrophenol (1 mM) and carbonylcyanide m-chlorophenylhydrazone and carbonylcyanide p-trifluoromethoxyphenylhydrazone (1--10 micrometer) and also by sodium azide. These data suggest that calcium uptake is dependent on energy and on a carrier. Calcium uptake is stimulated by pyrophosphate but not by ATP, orthophosphate, or polyphosphate. This stimulation is prevented by proton conductors or by incubation at 0 degrees C.
mesh_terms: D001386:Azides / Q000494:pharmacology; D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002413:Cations, Divalent; D004140:Dinitrophenols / Q000494:pharmacology; D011756:Diphosphates / Q000494:pharmacology*; D005658:Fungi / Q000378:metabolism*; D007700:Kinetics; D010838:Phytophthora / Q000187:drug effects / Q000378:metabolism*
chemical_list: D001386:Azides; D002413:Cations, Divalent; D004140:Dinitrophenols; D011756:Diphosphates; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D002118:Calcium