PMC:3216505 / 6667-7536 JSONTXT

{"project":"2_test","denotations":[{"id":"22355536-9428766-137225135","span":{"begin":648,"end":650},"obj":"9428766"}],"text":"The COPII proteins act jointly in membrane deformation\nNo differences in rigid tubulation were observed if nucleotide exchange on Sar1p was achieved by the addition of EDTA to lower Mg2+ (e.g., Fig. 2b) or by the addition of Sec12ΔCp (e.g., Fig. 2c). The presence of the N-terminal amphipathic helix of Sar1p was required for COPII recruitment (Fig. 2g). At a reduced concentration (one-tenth) of Sar1p, tubules nonetheless formed, albeit with a lower yield (Fig. 2f). We also noted that the outer Sec13/31p coat complex was required to observe separated tubules. When Sec13/31p was omitted as in reconstitution experiments of pre-budding complexes11, the GUVs aggregated, suggesting exposed hydrophobic contacts on the incomplete COPII coat (Fig. 2e vs. 2d, Fig. S2). These observations confirm the importance of Sar1p and the coordinated action of the COPII proteins."}