Consequences of the INCL disease mutations on the trafficking of CLN5. (A) HeLa cells were transiently transfected with wt CLN5 and PPT1Fin, carrying the most common INCL causing mutation. Cells were fixed with methanol 48 h post transfection, stained and analyzed by confocal microscopy. When wt CLN5 was co-expressed with wt PPT1Fin, wt CLN5 was able to traffic to lysosomes, whereas PPT1Fin retained in the ER. Scale bar 10 μm. (B) The GST-mCLN5 was used to pull down PPT1 carrying INCL disease mutations (PPTFin or the adult-onset causing mutation) and wild type CLN1/PPT1 from COS-1 cell lysates. Both PPTFin and the adult-onset mutations maintained their interaction with CLN5.