Fig. 13. Binding of L-FABP to intestinal ER membranes does not require ATP. (A) Intestinal ER (500 µg) was incubated with recombinant L-FABP (rL-FABP, 40 µg) in the absence or presence of ATP for 1 hour at 4°C. Post incubation, ER membranes were washed with cold PBS six times. 30 µg protein each of untreated intestinal ER (lane 1), ER treated with rL-FABP in the absence of ATP (lane 2), ER incubated with rL-FABP in the presence of ATP (lane 3) and native intestinal cytosol (lane 4) were separated by 15% SDS-PAGE, transferred to a nitrocellulose membrane, and L-FABP was identified by immunoblotting using ECL reagents for detection. A representative immunoblot is shown. (B) Densitometric analysis of L-FABP. The L-FABP bands shown in Fig. 13A were quantified using Image J software (NIH). Data are presented as arbitrary densitometry units (mean ± s.e.m.; n=4).