FIG. 1.

Pta1 is tightly associated with the CF II complex. (A) Fractions containing CF II from Q-Sepharose (QS) and poly(A)-Sepharose (PA) fractionations were subjected to immunoprecipitation with anti-Cft1 antibodies. The immunoprecipitated proteins were resolved on an SDS–8% polyacrylamide gel, and the gel was stained with silver. Four polypeptides, with sizes corresponding to those of CF II subunits, were coprecipitated (lanes 5 and 6). Lanes 3 and 4 are the unbound proteins from the supernatant. Lane 1 contains molecular mass standards (in kilodaltons), and lane 2 is an immunoprecipitation of the Q-Sepharose fraction with preimmune serum. The positions of the light and heavy chains of the immunoglobulins in lanes 2, 5, and 6 are indicated. (B) Immunoblot analysis of the CF II fraction from the Superose 6 step of CF II purification (lane 2) and proteins immunoprecipitated from the Q-Sepharose fraction with anti-Cft1 antibodies (lane 3). Blots were stained with a mixture of Brr5/Ysh1 polyclonal antibodies and a monoclonal antibody against Pta1.