Characterization of a connexin homologue in cultured soybean cells and diverse plant organs

Antibodies were prepared against ratliver connexin (27-kDa polypeptide subunit of cell gap junctions found between contacting animal cells) and a putative soybean (Glycine max (L.) Merr.) connexin (29-kDa polypeptide) previously isolated from cultured soybean root cells (SB-1 cell line). The antibodies were utilized to examine the intracellular localization of soybean connexin in these cultured soybean cells and to probe for the presence of a soybean-type connexin in petals, fruits, and leaves from a variety of plants. As judged by specific reactivity on immunoblots, both antibodies against the 27-kDa polypeptide (ratliver connexin) and against the 29-kDa polypeptide (operationally termed soybean connexin) were utilized to demonstrate immunological relatedness of the 27-kDa (rat liver) and the 29-kDa (soybean) polypeptide. Immunofluorescent localization of the putative soybean connexin in cultured soybean cells utilizing these probes demonstrated a peripherally localized punctate pattern of labeling at areas of contact between cells. Use of antibody to the soybean connexin as a probe on immunoblots of extracts from petals, fruits and leaves demonstrated that the soybean-type connexin is present in a large number of different plants.Abbreviations kDa kilodalton - IgG immunoglobulin G - NEPHGE non-equilibrium pH gradient electrophoresis - SDS-PAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis