POLYMER STRETCHING AND MEMBRANE DEFORMATION IN TETHERS OF PARTIALLY POLYMERIZED BILAYER

We consider tethers pulled from vesicles that are made of a membrane e mbedding polymers, e.g. a partially polymerized bilayer at a low degre e of polymerization, Assuming that straight polymers produce a ridge i n the stressed membrane, we deal with two effects, the alignment of po lymers parallel to the axis of the tether and the deformation of the i nitially circular cross section of the tether by the aligned polymers. Studying the cases of two or more parallel polymers and of a single p olymer, we calculate the free energy and the shape of the tether. Thre e or more polymers can collapse the tether, depending on their ridge a ngle. An estimate of the energies involved suggests that the stretchin g of polymers by tethers is practicable.