... Bank,Iowa City, IA, USA) and a-Scpep1 antisera derived fromrabbit and rat. Horseradish peroxidase- and fluorescence-conjugated secondary antibodies were supplied by Dianova(Hamburg, Germany) ... Ellen Ecker-mann-Felkl, Nicole Eiselt, Klaus Neifer, Leen vanAerschot and Dagmar Niemeier for excellent technicalassistance, and Bernhard Schmidt for MS expertise and advice. We thank Professor ... Ser-Asp-His[10,12]. To obtain an insight into the physiological and cellular function of the putative lysosomal SC Scpep1,we analysed the molecular properties of Scpep1 and generated an Scpep1 gene trap (Scpep1-gt)...