Figure 6.

CK2-phosphorylated FKBP52 does not bind HSP90. (A) Purified recombinant FKBP52 was phosphorylated by CK2 in the presence of [γ-³²P]ATP in vitro. HSP90-binding activity of FKBP52 was examined by native PAGE and CBB staining is shown. Lane I, HSP90 alone (3 μg); lane II, FKBP52 alone (2 μg); or lane III, FKBP52 (2 μg) was mixed with HSP90 (3 μg). The positions of HSP90, FKBP52, and FKBP52–HSP90 complexes are indicated by arrows. Outlines of protein bands are illustrated on the right with the numbers 1–4. (B) Bands 1–4 of A were excised and analyzed by re-electrophoresis on an SDS/polyacrylamide gel. CBB staining (Left) and corresponding autoradiography (Right) are shown. The positions of HSP90 and FKBP52 are indicated by arrows on the left.