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. Author manuscript; available in PMC: 2017 Jul 13.
Published in final edited form as: Methods Mol Biol. 2017;1486:357–390. doi: 10.1007/978-1-4939-6421-5_14

Fig. 1.

Fig. 1

Experimental setup to pull a single protein complex using dual-trap high-resolution optical tweezers. (A) A single gp41 complex in a fully folded six-helix bundle conformation is tethered between two polystyrene beads via a 2,260 bp DNA handle and pulled by increasing the trap separation (36). The extension and tension of the protein-DNA tether are detected. (B) SNARE construct used to measure the energetics and kinetics of SNARE assembly using optical tweezers (13). A fully assembled cytoplasmic synaptic SNARE complex is pulled from the C-termini of syntaxin and VAMP2 while crosslinked at the N-termini near the −6 layer. The SNARE complex consists of the N-terminal domain (NTD), the C-terminal domain (CTD), the linker domain (LD), and the N-terminal regulatory domain (NRD) in syntaxin. The positions of different layers are indicated by black numbers.