Open AccessCharacterization of specific binding sites for a mitogenic sulfated peptide, phytosulfokine‐α, in the plasma‐membrane fraction derived from Oryza sativa L.
Author(s) -
Matsubayashi Yoshikatsu,
Sakagami Youji
Publication year - 1999
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.1999.00409.x
Subject(s) - membrane , receptor , peptide , oryza sativa , cell growth , endogeny , binding site , cell membrane , biochemistry , cell , cell surface receptor , chemistry , biology , microbiology and biotechnology , gene
Treatment of rice cells with an endogenous mitogenic peptide, phytosulfokine‐α (PSK‐α), results in cell proliferation. In the present study, [ 3 H]PSK‐α prepared by catalytic reduction of a PSK‐α analog containing tetradehydroisoleucine was employed to identify putative PSK‐α target molecules on rice plasma membranes. Membrane binding of the ligand was found to be saturable, reversible and pH dependent. Scatchard analysis demonstrated the existence of both high‐ and low‐affinity binding sites with K d values of 1.4 n m and 27 n m , respectively. Competition studies with [ 3 H]PSK‐α and several PSK‐α analogs showed that displacing activity closely corresponds to the ability to induce cell proliferation. The properties of the binding sites distributed on plasma membranes are consistent with the function of PSK‐α receptors in activating a cascade of molecular events involved in plant cell proliferation.