Received September 27, 2002
Returned for revision November 12, 2002
Accepted December 20, 2002
Ethylene Rapidly Up-Regulates the Activities of Both Monomeric GTP-Binding Proteins and Protein Kinase(s) in Epicotyls of Pea
Igor E. Moshkov , Galina V. Novikova , Luis A.J. Mur , Aileen R. Smith , and Michael A. Hall *
Timiryazev Institute of Plant Physiology RAS, Botanicheskaya 35, Moscow 127276, Russia (I.E.M., G.V.N.); and Institute of Biological Sciences, University of Wales, Aberystwyth SY23 3DA, United Kingdom (L.A.J.M., A.R.S., M.A.H.)
* Corresponding author; email: mzh{at}aber.ac.uk.
It is demonstrated that, in etiolated pea (Pisum sativum) epicotyls, ethylene affects the activation of both monomeric GTP-binding proteins (monomeric G-proteins) and protein kinases. For monomeric G-proteins, the effect may be a rapid (2 min) and bimodal up-regulation, a transiently unimodal activation, or a transient down-regulation. Pretreatment with 1-methylcyclopropene abolishes the response to ethylene overall. Immunoprecipitation studies indicate that some of the monomeric G-proteins affected may be of the Rab class. Protein kinase activity is rapidly up-regulated by ethylene, the effect is inhibited by 1-methylcyclopropene, and the activation is bimodal. Immunoprecipitation indicates that the kinase(s) are of the MAP kinase ERK1 group. It is proposed that the data support the hypothesis that a transduction chain exists that is separate and antagonistic to that currently revealed by studies on Arabidopsis mutants.
