Figure 6

Immunoprecipitation of CABYR protein isoforms by anti-AKAP3 and anti-AKAP4. A, B: 2-D Western blots of immunoprecipitates from mouse sperm extracts using either anti-AKAP3 polyclonal antibody (A) or pre-immune serum (B) probed with anti-CABYR-A polyclonal antibody. CABYR-A protein isoform at 80 kDa, pI 4.5 is evident in immune complexes brought down by anti-AKAP3 but not by pre-immune serum. C, D: 2-D Western blot of immunoprecipitate from mouse protein extract using anti-AKAP4 monoclonal antibody (C) or normal mouse IgG (D) probed by anti-CABYR-A polyclonal antibody. The CABYR-A only variants of 80 kDa, pI 4.5 indicated by an arrow (C) were precipitated by anti-AKAP 4 antibody while normal mouse IgG immunoprecipitated no anti-CABYR immunoreactive proteins (D). 2-D Western blots of mouse sperm extract were immunoprecipitated using anti-AKAP3 polyclonal antibody (E), anti-AKAP4 monoclonal antibody (G), pre-immune serum (F), or normal mouse IgG (H) and probed by anti-CABYR-B polyclonal antibody. The 50 kDa, pI 6.5 spots indicated by arrows in E and G represent immunoprecipitated CABYR forms that contain both CABYR-A and CABYR-B and were recognized by antibody directed at CABYR-B.