Single event recording shows that docking onto receptor alters the kinetics of membrane fusion mediated by influenza hemagglutinin.

The initial steps of membrane fusion, receptor binding and membrane destabilization, are mediated by the envelope glycoprotein hemagglutinin of influenza virus. Interaction between these functions was determined from the time course of individual virion fusions to a planar membrane with and without receptor. With receptor, fusion was described by a Poisson process. In the absence of receptor, the time course was more complicated and could not be described with exponential rate constants. The conversion of a non-Markovian process into a simple Markov chain is direct evidence that receptor binding fundamentally alters the route of fusion.