  The formation of microparticles requires the bending of the plasma membrane
away from the cytosol. The capcity of the cell membrane to form a
microparticle, and the rate of membrane deformation, are controlled by multiple
factors, including loss of lipid asymmetry (primarily the exposure of
phosphatidylserine on the outer leaflet), detachment of the membrane from the
cortical cytoskeleton, and bleb expansion due to pressure. In this work, we
develop a biophysical model that accounts for the interaction between these
different factors. Our findings reveal that the linkage between the membrane
and cortex is a key determinant of outward budding. Ultimately, the rates and
mechanical parameters regulating cortical linkage interact with the kinetics of
phosphatidylserine flipping, laying out a mechanical phase space for regulating
the outward budding of the plasma membrane.
