  Vesicles are important surrogate structures made up of multiple phospholipids
and cholesterol distributed in the form of a lipid bilayer. Tubular vesicles
can undergo pearling i.e., formation of beads on the liquid thread akin to the
Rayleigh-Plateau instability. Previous studies have inspected the effects of
surface tension on the pearling instabilities of single-component vesicles. In
this study, we perform a linear stability analysis on a multicomponent
cylindrical vesicle. We solve the Stokes equations along with the Cahn-Hilliard
equations to develop the linearized dynamic equations governing the vesicle
shape and surface concentration fields. This helps us show that multicomponent
vesicles can undergo pearling, buckling, and wrinkling even in the absence of
surface tension, which is a significantly different result from studies on
single-component vesicles. This behaviour arises due to the competition between
the free energies of phase separation, line tension, and bending for this
multi-phospholipid system. We determine the conditions under which axisymmetric
and non-axisymmetric modes are dominant, and supplement our results with an
energy analysis that shows the sources for these instabilities. We further show
that these trends qualitatively match recent experiments.
