title: RALF, a 5-kDa ubiquitous polypeptide in plants, arrests root growth and development.
abstract: A 5-kDa polypeptide was isolated from tobacco leaves that induced a rapid alkalinization of the culture medium of tobacco suspension-cultured cells and a concomitant activation of an intracellular mitogen-activated protein kinase. An N-terminal sequence was obtained, and a cDNA coding for the 49-aa polypeptide was isolated from a tobacco cDNA library. The cDNA encoded a preproprotein of 115 amino acids that contained the polypeptide at its C terminus. A search among known expressed sequence tags revealed that genes encoding Rapid ALkalinization Factor (RALF) preproproteins were present in various tissues and organs from 16 species of plants representing 9 families. A tomato homolog of the polypeptide was synthesized and, when supplied to germinating tomato and Arabidopsis seeds, it caused an arrest of root growth and development. Although its specific role in growth has not been established, the polypeptide joins the ranks of the increasing number of polypeptide hormones that are known to regulate plant stress, growth, and development.
authors.affiliation: Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA.
authors.forename: G
authors.initials: G
authors.lastname: Pearce
authors.forename: D S
authors.initials: DS
authors.lastname: Moura
authors.forename: J
authors.initials: J
authors.lastname: Stratmann
authors.forename: C A
authors.initials: CA
authors.lastname: Ryan
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D008969:Molecular Sequence Data; D008970:Molecular Weight; D018521:Plant Physiological Phenomena; D010940:Plant Proteins / Q000737:chemistry / Q000302:isolation & purification* / Q000502:physiology; D021382:Protein Sorting Signals
chemical_list: D010940:Plant Proteins; D021382:Protein Sorting Signals