Identification and characterization of the human peroxin PEX3.
The biogenesis of peroxisomes requires the interaction of several peroxins, encoded by PEX genes and is well conserved between yeast and humans. We have cloned the human cDNA of PEX3 based on its homology to different yeast PEX3 genes. The deduced peroxin HsPEX3 is a peroxisomal membrane protein with a calculated molecular mass of 42.1 kDa. We created N- and C-terminal tagged PEX3 to assay its topology at the peroxisomal membrane by immunofluorescence microscopy. Our results and the one predicted transmembrane spanning region are in line with the assumption that H sPEX3 is an integral peroxisomal membrane protein with the N-terminus inside the peroxisome and the C-terminus facing the cytoplasm. The farnesylated peroxisomal membrane protein PEX19 interacts with HsPEX3 in a mammalian two-hybrid assay in human fibroblasts. The physical interaction could be confirmed by coimmunoprecipitation of the two in vitro transcribed and translated proteins. To address the targeting of PEX3 to the peroxisomal membrane, the expression of different N- and C-terminal PEX3 truncations fused to green fluorescent protein (GFP) was investigated in human fibroblasts. The N-terminal 33 amino acids of PEX3 were necessary and sufficient to direct the reporter protein GFP to peroxisomes and seemed to be integrated into the peroxisomal membrane. The expression of a 1-16 PEX3-GFP fusion protein did not result in a peroxisomal localization, but interestingly, this and several other truncated PEX3 fusion proteins were also localized to tubular and/or vesicular structures representing mitochondria.
Soukupova
M
M
Institut für Physiologische Chemie, Systembiochemie, Ruhr-Universität Bochum, Germany.
Sprenger
C
C
Gorgas
K
K
Kunau
W H
WH
Dodt
G
G
D018528:ATP-Binding Cassette Transporters; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002451:Cell Compartmentation; D002460:Cell Line; D005347:Fibroblasts / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics; D017930:Genes, Reporter; D005816:Genetic Complementation Test; D049452:Green Fluorescent Proteins; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D008074:Lipoproteins / Q000235:genetics / Q000378:metabolism*; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008830:Microbodies / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D000074401:Peroxins; D018901:Peroxisomal Disorders / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid
D018528:ATP-Binding Cassette Transporters; D005656:Fungal Proteins; D008074:Lipoproteins; D008164:Luminescent Proteins; D008565:Membrane Proteins; C109779:PEX19 protein, S cerevisiae; C070895:PEX3 protein, S cerevisiae; D000074401:Peroxins; C113138:Pex3 protein, human; D011993:Recombinant Fusion Proteins; C406793:SPF1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins