The ncd promoter drives expression of a fluorescence resonance energy transfer (FRET)-based sensor that is designed to measure tension along a gain-of-function ncd kinesin motor. The sensor consists of the full-length ncd coding sequence, with a Y485K mutation that reduces the strength of binding to ADP and increases the strength of binding to microtubules, resulting in a gain-of-function protein with increased motor velocity and mechanical output. A tension-sensing module (TSmod) has been inserted at K210 near the ncd tail-stalk junction. The tension-sensing module comprises two fluorescent proteins - mTFP1 (FRET donor) and Venus (FRET acceptor) - separated from each other by a stretchable domain from spider silk (PMID:20613844). Under low tension high FRET is produced, but under high tension, the two fluorophores move further apart, reducing the FRET signal.