INVITRO AND INVIVO PHOSPHORYLATION OF STOMATAL PHOSPHOENOLPYRUVATE CARBOXYLASE FROM VICIA-FABA L

The in vitro and in vivo phosphorylation of stomatal phosphoenolpyruvate carboxylase [EC 4.1. 1.31] from Vicia faba L. was demonstrated by feeding the concentrated enzyme after 0-70% ammonium sulfate precipitation of guard cell protoplasts with P-32 and subsequent analysis of autoradiograms and Western immunoblots, after SDS-PAGE, of protein samples. The in vitro and in vivo results provide evidence for a radioactive labeling of the two stomatal PEPCase bands (112 and 110 kDa).