Figure 8.

Srp102p-ΔTMD and Srp101p form a stable complex in the cytosol. A cytosolic extract was prepared from strains containing Srp102p-ΔTMD and Srp101p with or without an HA tag (lanes 1–3, Srp101p-HA, WBY752; anes 4– 6, no tag; WBY618 with pWB209). In A, 1 OD₆₀₀ equivalent of cell cytosol was subjected to immunoprecipitation with anti-HA mAbs coupled directly to agarose beads. Coimmunoprecipitated proteins were eluted from the beads, and were then subjected to SDS-PAGE followed by Western blot analysis using antisera against Srp102p. Eluates from the immunoprecipitation are shown in lanes 3 and 6 (E, eluate), while proteins not bound during the immunoprecipitation are shown in lanes 2 and 5 (S, supernatant). Lanes 1 and 4 (T, total) contain 1 OD₆₀₀ cell equivalent of whole-cell extract as a marker for the amount of Srp102p-ΔTMD that is in each of the immunoprecipitations. B shows the same type of experiment, but using the anti-Srp102p antibody coupled to beads to perform the immunoprecipitation followed by detection of Srp101p-HA with anti-HA mAbs. Note that lanes 4–6 are blank because the Srp101p present in those lanes has no HA epitope.