Differential subcellular localization of endogenous and transfected soluble epoxide hydrolase in mammalian cells: evidence for isozyme variants.
Endogenous, constitutive soluble epoxide hydrolase in mice 3T3 cells was localized via immunofluorescence microscopy exclusively in peroxisomes, whereas transiently expressed mouse soluble epoxide hydrolase (from clofibrate-treated liver) accumulated only in the cytosol of 3T3 and HeLa cells. When the C-terminal lie of mouse soluble epoxide hydrolase was mutated to generate a prototypic putative type 1 PTS (-SKI to -SKL), the enzyme targeted to peroxisomes. The possibility that soluble epoxide hydrolase-SKI was sorted slowly to peroxiosmes from the cytosol was examined by stably expressing rat soluble epoxide hydrolase-SKI appended to the green fluorescent protein. Green fluorescent protein soluble epoxide hydrolase-SKI was strictly cytosolic, indicating that -SKI was not a temporally inefficient putative type 1 PTS. Import of soluble epoxide hydrolase-SKI into peroxisomes in plant cells revealed that the context of -SKI on soluble epoxide hydrolase was targeting permissible. These results show that the C-terminal -SKI is a non-functional putative type 1 PTS on soluble epoxide hydrolase and suggest the existence of distinct cytosolic and peroxisomal targeting variants of soluble epoxide hydrolase in mouse and rat.
Mullen
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RT
Department of Plant Biology, Arizona State University, Tempe 85287-1601, USA.
Trelease
R N
RN
Duerk
H
H
Arand
M
M
Hammock
B D
BD
Oesch
F
F
Grant
D F
DF
D016475:3T3 Cells; D000818:Animals; D004851:Epoxide Hydrolases / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008322:Mammals; D051379:Mice; D008830:Microbodies / Q000201:enzymology; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012995:Solubility; D013347:Subcellular Fractions; D014162:Transfection
D007527:Isoenzymes; D011993:Recombinant Fusion Proteins; D004851:Epoxide Hydrolases