Fig. 5. The dileucine-like and WE motifs are sufficient for lysosomal/melanosomal targeting in MNT1 cells. (A) Quantitative immunofluorescence analysis of the subcellular distribution displayed by LAMP/OA1 chimeras in transiently transfected MNT1 cells. Following immunodecoration with anti-rat LAMP1 antibodies, transfected cells were counted and classified into three categories, based on the vesicular (VE), plasma membrane (PM) or mixed (MX) distribution of the recombinant proteins (see Materials and Methods for details). Results are expressed as the percentage of cells showing a specific distribution pattern and represent the mean ± s.e.m. of 3-5 independent experiments. The total number of cells counted is indicated. (B) Quantitative immunofluorescence analysis of the colocalization between LAMP/OA1 chimeras and endogenous OA1 in transiently transfected MNT1 cells. Cells were double labeled with anti-rat LAMP1 and anti-OA1 antibodies. Results are expressed as the percentage of double-positive vesicles out of all rat LAMP1-positive compartments per cell and represent the mean ± s.d. of the data pooled from 2-5 independent experiments. The number of vesicles and cells counted is indicated. No colocalization differences were noted between cells displaying vesicular or mixed distribution patterns of the recombinant proteins, thus all data concerning each chimera were pooled together.