title: Auxin-activated NADH oxidase activity of soybean plasma membranes is distinct from the constitutive plasma membrane NADH oxidase and exhibits prion-like properties.
abstract: The hormone-stimulated and growth-related cell surface hydroquinone (NADH) oxidase activity of etiolated hypocotyls of soybeans oscillates with a period of about 24 min or 60 times per 24-h day. Plasma membranes of soybean hypocotyls contain two such NADH oxidase activities that have been resolved by purification on concanavalin A columns. One in the apparent molecular weight range of 14-17 kDa is stimulated by the auxin herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The other is larger and unaffected by 2,4-D. The 2,4-D-stimulated activity absolutely requires 2,4-D for activity and exhibits a period length of about 24 min. Also exhibiting 24-min oscillations is the rate of cell enlargement induced by the addition of 2,4-D or the natural auxin indole-3-acetic acid (IAA). Immediately following 2,4-D or IAA addition, a very complex pattern of oscillations is frequently observed. However, after several hours a dominant 24-min period emerges at the expense of the constitutive activity. A recruitment process analogous to that exhibited by prions is postulated to explain this behavior.
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D006540:Herbicides / Q000494:pharmacology; D018546:Hypocotyl / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure; D007210:Indoleacetic Acids / Q000378:metabolism / Q000494:pharmacology*; D009097:Multienzyme Complexes / Q000145:classification / Q000187:drug effects / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000145:classification / Q000187:drug effects / Q000378:metabolism*; D010507:Periodicity; D010937:Plant Growth Regulators / Q000378:metabolism / Q000494:pharmacology*; D010940:Plant Proteins / Q000145:classification / Q000187:drug effects / Q000378:metabolism; D013025:Glycine max / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism / Q000648:ultrastructure; D013997:Time Factors
chemical_list: D006540:Herbicides; D007210:Indoleacetic Acids; D009097:Multienzyme Complexes; D010937:Plant Growth Regulators; D010940:Plant Proteins; D015084:2,4-Dichlorophenoxyacetic Acid; C030737:indoleacetic acid; C427863:ENOX1 protein, human; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases
keywords: NASA Discipline Cell Biology; Non-NASA Center