FIG. 3.

Overexpression of Fps1p in S. cerevisiae sec6 vesicles. Yeast endoplasmic reticulum (ER)-derived microsomes (lane 1) and sec6 vesicles prepared from cells containing a multicopy vector either lacking FPS1 (lane 2) or containing FPS1 (lane 3) were immunoblotted by using an antipeptide antibody prepared against amino acid residues 173 to 183 (HLSRRRSRSRA) and 161 to 168 (KNADDAHT) of Fps1p and antiserum prepared against Sec61p (an ER marker protein [23]). Quantitative immunoblotting indicated that sec6 vesicles are approximately twofold more depleted by Sec61p than are ER membranes.