Expression of the Daucus carota somatic embryogenesis receptor kinase (DcSERK) protein in insect cells.

The Daucus carota somatic embryogenesis receptor kinase (DcSERK) gene serves as marker to monitor the transition from somatic into embryogenic plant cells. To determine the intrinsic biochemical properties of the DcSERK protein, a predicted transmembrane receptor, the kinase domain was expressed as a 40-kDa his-tag fusion protein in the baculovirus insect cell system. The kinase domain fusion protein was able to autophosphorylate in vitro. Phosphoamino acid analysis of the autophosphorylated DcSERK protein revealed that it was autophosphorylated on serine and threonine residues. This is the first evidence of the biochemical characterization of a transmembrane receptor kinase from embryogenic plant cell cultures.