title: Amino acids--a life between metabolism and signaling.
abstract: Amino acids serve as constituents of proteins, precursors for anabolism, and, in some cases, as signaling molecules in mammalians and plants. This review is focused on new insights, or speculations, on signaling functions of serine, γ-aminobutyric acid (GABA) and phenylalanine-derived phenylpropanoids. Serine acts as signal in brain tissue and mammalian cancer cells. In plants, de novo serine biosynthesis is also highly active in fast growing tissues such as meristems, suggesting a similar role of serine as in mammalians. GABA functions as inhibitory neurotransmitter in the brain. In plants, GABA is also abundant and seems to be involved in sexual reproduction, cell elongation, patterning and cell identity. The aromatic amino acids phenylalanine, tyrosine, and tryptophan are precursors for the production of secondary plant products. Besides their pharmaceutical value, lignans, neolignans and hydroxycinnamic acid amides (HCAA) deriving from phenylpropanoid metabolism and, in the case of HCAA, also from arginine have been shown to fulfill signaling functions or are involved in the response to biotic and abiotic stress. Although some basics on phenylpropanoid-derived signaling have been described, little is known on recognition- or signal transduction mechanisms. In general, mutant- and transgenic approaches will be helpful to elucidate the mechanistic basis of metabolite signaling.
authors.affiliation: Department of Botany II, University of Cologne, Cologne Biocenter, Zülpicherstr. 47B, 50674 Cologne, Germany. Electronic address: rainer.haeusler@uni-koeln.de.
authors.forename: Rainer E
authors.initials: RE
authors.lastname: Häusler
authors.affiliation: Department of Botany II, University of Cologne, Cologne Biocenter, Zülpicherstr. 47B, 50674 Cologne, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Ludewig
authors.affiliation: Department of Botany II, University of Cologne, Cologne Biocenter, Zülpicherstr. 47B, 50674 Cologne, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Krueger
mesh_terms: D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D063245:Plant Development; D010944:Plants / Q000378:metabolism; D015398:Signal Transduction; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D000596:Amino Acids; D005680:gamma-Aminobutyric Acid
keywords: GABA; Hydroxycinnamic-acid-amides; Neolignans; Serine; Signaling