UC Berkeley

Molecular kinetics in living systems fundamentally shape the response function of signal transduction. Signaling cascades in cells are often initiated and amplified at the plasma membranes, where decisions are made under constant presence of molecular noise. Conceivably, the signaling geometry of membrane reactions are intimately related to the system’s ability to robustly detect signals, down to single-molecule level. However, the physical mechanisms of signal transduction embedded in membrane signaling reactions are poorly understood. One of the limitations stems from a lack of well-controlled experimental assay to conceptualize the role of stochastic processes in membrane signaling. In this dissertation, I attempt to lessen this gap by developing single-molecule assays accompanied with statistical kinetics theory to analyze the molecular processes of reconstituted biochemical systems, derived from T-cell receptor triggering, on supported membranes. Broadly speaking, cytosolic proteins in membrane signaling reactions commonly follow a membrane recruitment-activation protocol. Therefore, the content of this dissertation will begin by discussing the role of membrane recruitment in signaling accuracy, with specific emphasis on kinetic proofreading. The later section focuses on the activities after successful activation, from determination of simple catalysis to elaboration of a bistable network response. These discourse hopefully provide a basis to discuss the design principles underlying signaling reactions.