Munc18 proteins bind non-cognate Sxs.

Sx1_1-261-His or Sx4_1-275-His were incubated with detagged Munc18a or Munc18c for 2 h, 24 h or 48 h before the Sx was immobilized onto TALON^™ Co²⁺ affinity beads for 1h and then washed. Samples of the beads were then run on SDS-PAGE and stained with Coomassie Blue to determine if detagged Munc18 had been pulled down by cognate and non-cognate Sx partners. Detagged Munc18a and Munc18c were also incubated for the same time periods on beads without bound Sx to monitor non-specific binding (control lanes). Solid vertical lines on the gel image denote the removal of intervening lanes or placing two different gels adjacent to each other.