Lateral remodeling of phase-separated membranes containing nonblocked azo-sphingolipids upon light trigger analyzed by high-speed AFM. (A and B) Changes in the area of Lo domains (of depicted snapshots) before/after illumination with UV-A (λ = 365 nm) and blue (λ = 470 nm) lights on DOPC:Chol:SM:photolipid (10:6.7:5:5 mol ratio) SLBs having (A) Azo-β-Gal-Cer (see Video S1), Azo-SM (see Video S2), or Azo-Cer (see Video S3) with a sphingosine backbone (X = –H) and varying headgroup functionality (R = galactosyl, phosphocholine, or –OH, respectively) or (B) Azo-α-Gal-PhCer (see Video S5) or Azo-PhCer (see Video S6) with a phytosphingosine backbone (X = –OH) and varying headgroup functionality (R = galactosyl or –OH, respectively). (C and D) Reversible lateral remodeling of a phase-separated SLB containing Azo-SM (DOPC:Chol:SM:Azo-SM; 10:6.7:5:5 mol ratio) upon UV-A/blue light irradiation, as seen in Video S4. (C) AFM images of the SLB at the dark-, UV-, and blue light-adapted states, displaying the area occupied by the Lo phase and the Ld-Lo height mismatches. (D) Relative variation of total Lo area of the SLB over time, shown in Video S4, upon shining short pulses (marked with arrows) of UV-A and blue light. To see this figure in color, go online.