AtPEX2 and AtPEX10 are targeted to peroxisomes independently of known endoplasmic reticulum trafficking routes.
Controversy exists in the literature over the involvement of the endoplasmic reticulum (ER) in the delivery of membrane proteins to peroxisomes. In this study, the involvement of the ER in the trafficking of two Arabidopsis (Arabidopsis thaliana) peroxisomal membrane proteins was investigated using confocal laser scanning microscopy of living cells expressing fusions between enhanced yellow fluorescent protein (eYFP) and AtPEX2 and AtPEX10. The fusion proteins were always detected in peroxisomes and cytosol irrespective of the location of the eYFP tag or the level of expression. The cytosolic fluorescence was not due to cleavage of the eYFP reporter from the C-terminal fusion proteins. Blocking known ER transport routes using the fungal metabolite Brefeldin A or expressing dominant negative mutants of Sar1 or RabD2a had no effect on the trafficking of AtPEX2 and AtPEX10 to peroxisomes. We conclude that AtPEX2 and AtPEX10 are inserted into peroxisome membranes directly from the cytosol.
Sparkes
Imogen Averil
IA
School of Biological and Molecular Sciences, Oxford Brookes University, UK. isparkes@brookes.ac.uk
Hawes
Chris
C
Baker
Alison
A
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001693:Biological Transport, Active; D003600:Cytosol / Q000378:metabolism; D018744:DNA, Plant / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D000074401:Peroxins; D020675:Peroxisomes / Q000378:metabolism; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins; D001426:Bacterial Proteins; D018744:DNA, Plant; D008164:Luminescent Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C477605:PEX10 protein, Arabidopsis; D000074401:Peroxins; D011993:Recombinant Fusion Proteins; C462525:TED3 protein, Arabidopsis; C054562:yellow fluorescent protein, Bacteria