Fig. 3. TL-CAT constructs are associated with the detergent-insoluble cytoskeleton. 3T3 cells were transiently transfected with CAT, TS-CAT or TL-CAT under the control of the constitutive PGK promoter, and assayed for CAT immunoreactivity in detergent-extracted cell lysates as described in Materials and Methods. CAT protein expression on the cell surface was approximately 7-fold higher in TL-CAT transfectants as compared with CAT alone transfectants, and CAT expression on the surface of TS-CAT transfectants remained near control levels. Eighty-one percent of the CAT immunoreactivity on the cell surface of TL-CAT transfectants was associated with the detergent-insoluble cytoskeleton. In contrast, detergent-insoluble immunoreactivity was similar between CAT and TS-CAT transfectants. The results represent the average (±s.e.m.) of 4 experiments, each performed in triplicate, and each assay normalized to the TL-CAT values.