cDNA Cloning and Characterization of a Constitutively Expressed Isoform of the Human Peroxin Pex11p

We cloned a human cDNA encoding an isoform of the peroxin Pex11p, termed Pex11pβ, by screening of human liver cDNA library using as a probe human EST-derived, ∼300 bp-long nucleotides showing homology toPEX11fromCandida boidiniiandSaccharomyces cerevisiae. PEX11β encoded a protein comprising 259 amino acids, with two putative transmembrane segments, showing ∼40% identity to inducible Pex11pα, at the amino acid sequence level. Pex11pβ was found to be a peroxisomal protein, as assessed by colocalization with acyl-CoA oxidase, an enzyme catalyzing the first step of peroxisomal β-oxidation system, in Pex11pβ-expressing Chinese hamster ovary cells.PEX11β was not induced in rats by treatment of clofibrate, a peroxisome proliferator, in contrast toPEX11α.