Purification, Characterization, and cDNA Cloning of ProfiIin from Phaseo/us vu/garis'

Profilin from common bean (Phaseolus vulgaris 1.) was purified to homogeneity by poly-i-Pro affinity chromatography and gel filtration. The hypocotyl and symbiotic root nodule protein was detected as a single isoform with a 14.4-kD molecular mass and an isoelectric point of 5.3. Partia1 amino acid and DNA sequencing of a full-length cDNA clone confirmed its identity as profilin. An antibody generated against the purified protein binds to a protein with the same molecular mass in leaves and nodules. Immunolocalization of the protein showed a diffuse distribution in the cytoplasm of hypocotyls and nodules but enhanced staining at the vascular bundles. The strong identity of the sequence among the profilins of birch, maize, and bean suggests that it may play an important role in the signal transduction mechanism of plant cells and plantbacterial symbioses.