Fig. 1. CaSEC3 is a true homologue of ScSEC3. (A) CaSEC3 can partially rescue the temperature sensitivity of Scsec3 mutants. Cells of S. cerevisiae NY2449 (SEC3), NY2448 (Scsec3), and WYL68 (derived by transforming NY2448 with CaSEC3 under control of the ScSEC3 promoter on a CEN plasmid) were first grown overnight in synthetic medium, diluted, and streaked onto YPD plates for incubation at 22, 30 and 37°C for 2 days. (B) Casec3 cells accumulated secretory vesicles in the cytoplasm. Cells of SC5314 (SEC3) and WYL28 (sec3) were first grown at 30°C overnight in GMM and then diluted into fresh YPD medium for further growth at 37°C for 3 hours before electron microscopy. Bar, 0.5 µm. (C) Sec3p-GFP localized to sites of cell growth. Synchronized G1 cells of WYL30 that expresses Sec3p-GFP were grown in GMM at 30°C to exponential phase (left panel). Hyphal cells (right panel) were induced in GMM supplemented with 10% serum at 37°C, and samples were collected at the indicated times for microscopy. Bar, 5 µm.