Figure 3. Expression and solubilization of ABCA4 C-terminal mutants.

Membranes from HEK 293T cells expressing WT and mutant ABCA4 and containing the 1D4 tag were treated with detergent and the amount of ABCA4 was quantified on Western blots labeled with the Rho 1D4 antibody. (A) Relative expression of ABCA4 mutants was determined from membranes solubilized with SDS; (B) Relative solubilization was determined by solubilizing membranes in 18 mM CHAPS and removing unsolubilized material by centrifugation prior to SDS gel electrophoresis and Western blotting. (C) Normalized solubilization was determined from the ratio of CHAPS solubilization to the level of expression determined from SDS solubilized membranes and expressed as a % of WT ABCA4. Inserts show representative examples of western blots of the ABCA4 mutants. A doublet band was present in SDS solubilized samples and a single sharp band was observed for CHAPS solubilized samples suggesting that poorly processed ABCA4 was not solubilized by CHAPS. Quantitative data are an average from 3 or more independent experiments ± SD.