INVESTIGATION OF THE ENERGY REQUIREMENT AND TARGETING SIGNAL FOR THE IMPORT OF GLYCOLATE OXIDASE INTO GLYOXYSOMES

The uptake of glycolate oxidase into peroxisomes has been studied usin g an in vitro import system. Import of glycolate oxidase was found to be ATP-dependent and temperature-dependent and specific for glyoxysome s. In these respects it resembles the import of isocitrate lyase into both glyoxysomes and leaf-type peroxisomes; thus the ATP-dependence an d temperature dependence appear to be general properties of plant micr obody protein import. Two mutant versions of glycolate oxidase were pr epared lacking 59 amino acids of the N-terminus and 53 amino acids of C-terminus, respectively. Both were capable of ATP-dependent import, w hereas a fusion protein consisting of the cytosolic protein dihydrofol ate reductase linked to the last 20 amino acids of glycolate oxidase b ound to glyoxysomes but did not enter the organelle.