PEX3 functions as a PEX19 docking factor in the import of class I peroxisomal membrane proteins.
PEX19 is a chaperone and import receptor for newly synthesized, class I peroxisomal membrane proteins (PMPs). PEX19 binds these PMPs in the cytoplasm and delivers them to the peroxisome for subsequent insertion into the peroxisome membrane, indicating that there may be a PEX19 docking factor in the peroxisome membrane. Here we show that PEX3 is required for PEX19 to dock at peroxisomes, interacts specifically with the docking domain of PEX19, and is required for recruitment of the PEX19 docking domain to peroxisomes. PEX3 is also sufficient to dock PEX19 at heterologous organelles and binds PEX19 via a conserved motif that is essential for this docking activity and for PEX3 function in general. Not surprisingly, transient inhibition of PEX3 abrogates class I PMP import but has no effect on class II PMP import or peroxisomal matrix protein import. Taken together, these results suggest that PEX3 plays a selective, essential, and direct role in PMP import as a docking factor for PEX19.
Dept. of Biological Chemistry, The Johns Hopkins University School of Medicine, 725 North Wolfe St., Baltimore, MD 21205, USA.
Yi
Y
Fang
James C
JC
Morrell
Jacob M
JM
Jones
Stephen J
SJ
Gould
D020816:Amino Acid Motifs; D002460:Cell Line; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D006801:Humans; D008074:Lipoproteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D000074401:Peroxins; D020675:Peroxisomes / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
D008074:Lipoproteins; D008565:Membrane Proteins; D000074401:Peroxins; C113138:Pex3 protein, human; D034741:RNA, Small Interfering; D029701:Saccharomyces cerevisiae Proteins; C087343:PEX19 protein, human