Antibodies against Pex14p block ATP-independent binding of matrix proteinsto peroxisomes in vitro

The membrane protein Pex14p is a key component of the protein import machin ery of peroxisomes, Antibodies raised against human Pex14p recognise a 66 k Da protein in sunflower glyoxysomes (HaPex14p) and immunoprecipitate in vit ro-translated Arabidopsis Pex14p (AtPex14p). These antibodies inhibit the A TP-independent binding to sunflower peroxisome membranes of peroxisome targ eting signal type (PTS) 1- and PTS2-targeted matrix proteins, but not an in tegral membrane protein. These results suggest that Pex14p functions before the ATP-dependent step of peroxisome assembly. (C) 1999 Federation of Euro pean Biochemical Societies.