Figure 5.

HDL-Sepharose affinity chromatography of extracts of RA/Bt₂cAMP-treated and untreated F9 cells. Profiles shown in a and b were from [¹²⁵I]-surface-labeled cells, whereas c–e were from unlabeled cells. (a) Coomassie-stained gel of proteins eluted from HDL-Sepharose by using 1, 4, and 8 M urea-containing buffer (lanes 3–8). Lanes 1 and 10 contain aliquots of detergent extracts from each cell type. Molecular weight standards are in lanes 2 and 9. (b) Autoradiograph of the gel shown in a. (c) Immunoblot analysis of detergent extracts of RA/Bt₂cAMP-treated (lane 1) and untreated (lane 2) F9 cells by using megalin and cubilin antibodies. (d) Silver-stained SDS/PAGE profile of sequential fractions eluted from HDL-Sepharose by using 8 M urea-containing buffer. Lane 1 contains molecular weight standards, lanes 2–5 correspond to HDL-Sepharose eluted fractions from extracts of RA/Bt₂cAMP-treated F9 cells, lane 6 is blank, and lanes 7–10 are HDL-Sepharose eluted fractions from untreated F9 cells. (d) Anticubilin immunoblot analysis of the same fractions shown in c.