CDNA cloning and characterization of the third isoform of human peroxin Pex11p

Abstract

We have cloned a human cDNA encoding an isoform of the peroxin Pex11p, termed Pex11pγ, by BLASTP homology search on eukaryotic protein database and reverse transcription (RT)-PCR of human fibroblast RNA. Pex11pγ was 241 amino-acid long, with two putative transmembrane segments, showing 22% and 23% amino-acid identity to Pex11pα and Pex11pβ, respectively. PEX11 γ gene was located on chromosome 19, distinct from PEX11 α and PEX11 β. Pex11pγ was found to be a peroxisomal membrane protein, as assessed by colocalization with peroxisome targeting signal type 1 (PTS1)-proteins, in epitope-tagged Pex11pγ-expressing Chinese hamster ovary cells. Pex11pγ exposes both of the N- and C-terminal parts to the cytosol. PEX11 γ was not induced in rats by treatment of clofibrate, a peroxisome proliferator, similar to constitutively expressed PEX11 β but in contrast to inducible PEX11 α.