title: Secondary messengers and phospholipase A2 in auxin signal transduction.
abstract: Despite recent progress auxin signal transduction remains largely scetchy and enigmatic. A good body of evidence supports the notion that the ABP1 could be a functional receptor or part of a receptor, respectively, but this is not generally accepted. Evidence for other functional receptors is lacking, as is any clearcut evidence for a function of G proteins. Protons may serve as second messengers in guard cells but the existing evidence for a role of calcium remains to be clearified. Phospholipases C and D seem not to have a function in auxin signal transduction whereas the indications for a role of phospholipase A2 in auxin signal transduction accumulated recently. Mitogen-activated protein kinase (MAPK) is modulated by auxin and the protein kinase PINOID has a role in auxin transport modulation even though their functional linkage to other signalling molecules is ill-defined. It is hypothesized that signal transduction precedes activation of early genes such as IAA genes and that ubiquitination and the proteasome are a mechanism to integrate signal duration and signal strength in plants and act as major regulators of hormone sensitivity.
authors.affiliation: Universität Hannover, Institut für Zierpflanzenbau, Baumschule und Pflanzenzüchtung, Hannover, Germany. scherer@zier.uni-hannover.de
authors.forename: Günther F E
authors.initials: GF
authors.lastname: Scherer
mesh_terms: D029681:Arabidopsis Proteins; D001692:Biological Transport; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007210:Indoleacetic Acids / Q000378:metabolism / Q000494:pharmacology*; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D010937:Plant Growth Regulators; D010940:Plant Proteins; D010944:Plants / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D011956:Receptors, Cell Surface / Q000502:physiology; D015290:Second Messenger Systems / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins; D011956:Receptors, Cell Surface; C046131:auxin receptor, plant; C405165:PINOID protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases; D010741:Phospholipases A; D054467:Phospholipases A2