The organic anion transport inhibitor, probenecid, inhibits the transport of Lucifer Yellow at the plasma membrane and the tonoplast in suspension-cultured plant cells

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Abstract
In this paper we report on the uptake of the membrane-impermeant fluorescent probe Lucifer Yellow CH (LY-CH) into the vacuolar system of plant cell suspension cultures. LY-CH is internalised into vacuoles of maize cells at a faster ‘rate’ than carrot cells and in each case, the probe is also trapped at the cell wall. In the presence of the uricosuric drug probenecid, the vacuolar uptake of LY-CH by carrot and maize cells is inhibited and in some cells internalisation of probe is blocked at the plasma membrane. In electroporated carrot cells, LY-CH is sequestered slowly from the cytoplasm into vacuoles by a probenecid-inhibitable transport process. These results are compared with the effects of probenecid on the sequestration of LY-CH from the cytoplasm into the lysosomal system of fibroblasts. In view of the above findings and recent evidence for the putative uptake of LY-CH by fluid-phase endocytosis in plant cells, the possibility that LY-CH is transported across plant membranes via probenecidinhibitable organic anion transporters is discussed