Figure 1.

Albumin affinity purification of cubilin. (a) Eluted fractions were analyzed by SDS-PAGE and Coomassie stained. Lane 1: 0.1 μg of RAP affinity purified rabbit megalin; lane 2: IF-B₁₂ affinity purified cubilin. Lanes 3–11: fractions 4–12 (12 μL/lane). The positions of standard molecular weight markers are indicated. A strong band corresponding to the size of cubilin is clearly identified in fractions 5–8. Faint low–molecular-weight bands are seen with both the IF-B₁₂ purified and albumin purified cubilin. (b) The eluted protein was further identified as cubilin by immunoblotting using anti-rat cubilin antibodies.