Involvement of GTP-binding Protein Immunologically Resembled Gαs and Gαolf in Phytoalexin Production of Cultured Carrot

Abstract

A 38 kDa peptide in microsomal fraction prepared from oligogalacturonide elicitor-treated carrot cell culture showed an affinity to GTP after the separation by SDS-PAGE. Antibodies raised against the related alpha subunits of heterotrimer GTP-binding protein, anti-Gαs and anti-Gαolf, were found to crossreact with this peptide. In contrast, anti-G-proteins against other classes of α subunits of the trimeric complexes and low molecular weight monomers did not show the affinity to the peptide. These results suggest that a heterotrimer GTP-binding protein complex of which α subunit immunologically resembles Gαs and Gαolf may be involved in the early stage of oligouronide elicitor-induced phytoalexin biosynthesis in cultured carrot cells.