1 2 dioleoyl sn glycero 3 phosphocholine dopc

1,2-dioleoyl-sn-glycero-3-phospho-L-serine (DOPS) (Avanti Polar Lipids), 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) (Anatrace), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) (Avanti Polar Lipids) and cholesterol (Sigma) were dissolved in chloroform and mixed (3:2:3:2 w/w ratio). The lipid mix was dried under nitrogen gas and rehydrated in Buffer A. Liposomes were extruded through a 100 nm polycarbonate membrane (Whatman) to create a monodisperse unilamellar liposome population.

For the
single-particle tracking experiments, the following molar ratios,
74.5% of 1,2-dioleoyl-sn-glycero-3-phosphocholine
(DOPC, 350 μg) (Anatrace), 5% 1,2-dioleoyl-sn-glycero-3-phosphatidylserine (DOPS) (Anatrace), 20% of cholesterol
(Sigma-Aldrich), and 0.5% of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(lissamine
rhodamine B sulfonyl) (Rh-PE) (Avanti), were combined in a disposable
glass vial (all dissolved in chloroform). For control experiments,
the composition 79.5% DOPC, 20% cholesterol, and 0.5% Rh-PE was used.
In the case of membranes containing biotin, 1% biotinyl PE (Avanti)
was used instead of DOPC. For optical tweezers experiments, the composition
was 74% DOPC (70 μg), 5% DOPS (Anatrace), 20% cholesterol, and
1% Rh-PE. The chloroform was dried under argon and then under vacuum
for 1–2 h. Next, the lipids were rehydrated with 1 mL of rehydration
buffer containing 150 mM NaCl (Carlo Erba Reagents) and 20 mM 4-(2-Hydroxyethyl)-1-Piperazineethanesulfonic
Acid (HEPES), pH 7.5 (Thermo Fisher) for 10 min at room temperature
(RT). For single-particle tracking, the lipids were rehydrated in
the same way but with tris(hydroxymethyl)aminomethane (TRIS, Bio-Lab)
buffered saline (TBS). The rehydrated lipids were further extruded
(Avanti miniextruder) 13 times, using a 0.1 μm membrane (Whatman),
to form homogeneous SUVs.