Phosphate Translocator of Mesophyll and Bundle Sheath Chloroplasts of a C(4) Plant, Panicum miliaceum L. : Identification and Kinetic Characterization.

The phosphate translocator was identified in the envelope membranes of both mesophyll and bundle sheath chloroplasts of Panicum miliaceum L. by labeling with [1,2-(3)H]1,2-(2,2' -disulfo-4,4' -diisothiocyano)diphenylethane ([(3)H]H(2)DIDS) and by using SDS-PAGE. Assay of (32)Pi uptake by the chloroplasts showed that the phosphate translocators of both types of chloroplasts have a higher affinity for phosphoenolpyruvate than the C(3) counterpart and can be regarded as C(4) types.