Properties of substrate hydrolysis and product retention in fibroblasts expressing heterogeneous levels of GC. Fluorescence data on 10,000 viable cells was collected by FACS, as described, and is displayed in histogram form. The fluorescence profiles of fibroblasts incubated in the absence of substrate are shown for each experiment. (A) To determine the role of GC in PFBFDGlu hydrolysis, nontransduced, or MFG-GC transduced fibroblasts were incubated in the presence of 1 mmol/L CBE for 30 minutes at 37°C before incubation in the presence of 1 mmol/L PFBFDGlu. The MF values of each population are included above each histogram. (B) To determine the pH sensitivity of substrate hydrolysis, nontransduced or sorted MFG-GC transduced cells were incubated in the presence or absence of 600 μmol/L chloroquine during the last 5 minutes of 1 mmol/L CMFDGlu loading, as described above. (C) Fluorescence histograms of nontransduced, sorted MFG-GC transduced, or a 7.5:1 mix of nontransduced and sorted MFG-GC transduced cells incubated in the presence of 1 mmol/L CMFDGlu. Note: data shown in B and C was collected in the same experiment.