The fusion pore formed during a lingering kiss acts as a molecular filter mediating selective content release. Cartoon showing the solution structures of IL-8 (data from PDB structure 2IL8), mCherry (data from PDB structure 2H5Q), eotaxin-3 (data from PDB structure 1G2T), and the estimated size of Proregion28 relative to the dimensions of the fusion pore formed during a lingering kiss. Also shown are cartoons of the membrane proteins CD63 and P-selectin (full crystal structures are not available for either protein). P-selectin is shown as both a monomer and a dimer35 in the extended conformation observed for the detergent-purified membrane form of this molecule.34 Disordered polymers of multimeric VWF form a “ball of yarn” configuration under nonshear conditions26 and are shown here as a mottled background within the WPB lumen.
