(A) Schematic of the Tlg2 constructs used. (B) Size exclusion chromatography of MBP-Tlg21-327. The predicted position for a monomer, based on size standards, is indicated. (C) Size-exclusion chromatography of the MBP-tagged C. thermophilum SNARE motifs of Tlg2 (Qa-SNARE), Snc2 (R-SNARE), Vti1 (Qb-SNARE), and Tlg1 (Qc-SNARE). (D–F) Sedimentation velocity analytical ultracentrifugation (AUC) and derived parameters (insets). For MBP-Tlg2258-327 (panel D), the experimental molecular weight (181 kDa) falls between those expected for a trimer (161 kDa) and a tetramer (214 kDa); for untagged Tlg2258-327 (panel F), the experimental molecular weight (33.8 kDa) is in excellent agreement with that expected for a tetramer (33.6 kDa). The Habc domain (Tlg279-200) sediments as a monomer (panel E). For data and fits, see Figure 5—figure supplement 1.