Mechanism of Lck Recruitment to the T‐Cell Receptor Cluster as Studied by Single‐Molecule‐Fluorescence Video Imaging

Molecular movies: The Src-family kinase Lck is recruited to the site of Tcell receptor (TCR) clustering at very early stages after TCR engagement. The authors have investigated the mechanism of Lck recruitment to the TCR cluster by monitoring the movement of single molecules of Lck and its N-terminal ten amino acid sequence (N10; for experimental procedure see picture), both fused with green fluorescent protein (GFP) and expressed in the Jurkat Tcell line. Single-molecule observations revealed that neither Lck- nor N10-GFP underwent directed movement toward the cluster, but they both underwent apparent short-term simple Brownian diffusion.