Figure 6
Sar1p-GTP regulates ER to Golgi traffic of GCS90 and induces the disappearance of the punctate structures. CLSM analysis of Nicotiana tabacum leaf epidermal cells expressing GFP-fusions simultaneously with Sar1p variants. Sar1p-mRFP (A) and Sar1p-GTP-mRFP (B) are accumulated at the ER. Because Sar1p-GTP-mRFP blocks ER exit, membrane proteins accumulate in the ER and the ER membrane morphology turns into fenestrated sheets (B). In presence of Sar1p-GTP-mRFP, the Golgi fusion R/LGCS90 is blocked in the ER (C, compare with pattern presented Figure 5G). When GCS90 (D-F), R/L6-7GCS90 (G-I) or R/L10-12GCS90(J-L) are co-expressed with Sar1p-GTP-mRFP, the expression patterns remain unchanged, (compare to Figure 7G-I, A-C and D-F, respectively), except that the punctate structures have disappeared. Bars = 8 μm.