TABLE 1.

Nonspecific interactions between tips and coverslips

Tip	Coverslip	Positive	Tested	Positive (%)
Ni2+	Ni2+	350	350	100.0
Sx1A-H6	Sb2-H6	465	468	99.4
H6	Sb2-H6	200	200	100.0
Sx1A-H6	H6	320	320	100.0
Sx1A-H6 + GST-Sb2	Sb2-H6	1478	1482	99.7
Sx1A-H6	Sb2-H6 + GST-Sx1A	1372	1378	99.6
Sx1A-H6 + Sb2-H6	Sb2-H6	498	500	99.6
Sx1A-H6	Sb2-H6 + Sx1A-H6	493	494	99.8

Note: Nonspecific interactions refer to the bcd segment of the force-distance curves (see Figs. 1 E and 2 A); retraction velocity is 1.6 μm/s.

Abbreviations: GST, glutathione S-transferase; H6, six consecutive histidines tag; Sb2, synaptobrevin 2; Sx1A, syntaxin 1A.