Figure 1.

Polarization microscopy to study desmosome protein organization. (a) Shown here is a ribbon diagram of the Dsg3-ΔEA-GFP chimeric protein. Dsg3 extracellular domains EC1-4 (purple) and GFP (green) with the EA domain deletion/GFP insertion sites are indicated by black arrowheads and the transition dipole moment (μ) by the red double-headed arrow. (b) The fluorophore transition dipole (μ; red arrow) is described by azimuthal (α) and polar (β) angles in a spherical coordinate system where x-y is the imaging plane and z is the optical axis. (c) If Dsg3 is ordered, fluorescence intensity will be modulated by the excitation polarization, resulting in a sinusoidal curve with an amplitude dependent on the polar angle as shown for β = 20°, 25°, 30°, and 35°. (d) If Dsg3 is disordered, the fluorescence intensity will be constant regardless of the excitation polarization. To see this figure in color, go online.