Fig. 4. Yeast SRP contains two Srp14ps. (A) Extracts of strains expressing either wild-type and HA-Srp14p (lanes 1–5) or just HA-Srp14p (lanes 6–10) were immunoprecipitated with anti-HA (lanes 2 and 7) or anti-Sec65p antibodies (lanes 4 and 9). Material corresponding to 50% used in each immunoprecipitation (lanes 1 and 6) and of each supernate (lanes 3, 5, 8 and 10) and all immunoprecipitated material were analysed. (B and C) As (A) except that strains used expressed protein A-tagged Srp72p and wild-type Srp72p (B) or Myc-Srp21p and HA-Srp21p (C). Proteins were isolated using IgG–Sepharose or the antibody indicated. *, Ig chains recognized by secondary antibodies.