PEROXISOME BIOGENESIS - INVOLVEMENT OF ARF AND COATOMER

Peroxisomal membrane protein (Pmp)26p (RnPex11p). a major constituent of induced rat liver peroxisomal membrane, was found to contain a COOH -terminal, cytoplasmically exposed consensus dilysine motif with the p otential to bind coatomer, Biochemical as well as immunocytochemical e vidence is presented showing that peroxisomes incubated with preparati ons of bovine brain or rat liver cytosol recruit ADP-ribosylation fact or (ARF) and coatomer in a strictly guanosine 5'-O-(3-thiotriphosphate )-dependent manner. Consistent with this observation, IdlF cells expre ssing a temperature-sensitive mutant version of the epsilon-subunit of coatomer exhibit elongated tubular peroxisomes possibly due to impair ed vesiculation at the nonpermissive temperature. Since overexpression of Pex11p in Chinese hamster ovary wild-type cells causes proliferati on of peroxisomes, these data suggest that Pex11p plays an important r ole in peroxisome biogenesis by supporting ARF-and coatomer-dependent vesiculation of the organelles.