Figure 2. Chemical Crosslinking of the Neck Linker in an Extended Kinesin Increases the Velocity of Movement(A) A unique cysteine residue was added to the N terminus of the 13P insertion in a cys-light kinesin construct.(B) Specific interchain crosslinking of Cys-13P, but not 13P, induced by a bifunctional crosslinking agent (Coomassie stained SDS-PAGE gel).(C) Speed histogram of single Cys-13P molecules without crosslinking shows a peak at 116 nm/s.(D) After crosslinking, Cys-13P shows a second peak at higher speeds centered around 250 nm. The bimodal distribution of steps agrees with mixed populations of crosslinked and non-crosslinked kinesin observed in SDS-PAGE.