Biosynthesis and transport kinetics of wild type and mutant proteins. COS-1 cells were transiently transfected with cDNAs encoding the wild type LPH, LPH-Y1473X or LPH-D1796fs and used 48 h after transfection. A) The cells were metabolically labeled with [35S] methionine for 6 h continuously, lysed, immunoprecipitated with mAb anti-LPH and treated with endo H. B) The cells were labeled with [35S] methionine for 2 h and chased for 0, 4, 8 and 12 h, followed by cell lysis and immunoprecipitation. In all these experiments, the proteins were subjected to SDS-PAGE and autoradiography. The quantification was performed by Quantity One® software.