Annexin 5 decreases the diffusion of lipid and channel molecules in an artificial lipid bilayer

Abstract

The effects of annexin 5 on the lateral diffusion of single molecule lipids and single molecule proteins were studied in a lipid bilayer membrane. Single β-BODIPY HPC and ryanodine receptor type 2 (RyR2) labeled with Cy5 molecules were monitored by fluorescence microscopy. The diffusion coefficient was calculated in the presence and absence of annexin 5. The diffusion coefficients of β-BODIPY HPC and RyR2 were 11 × 11 × 10 -8 cm2/s and 2.7 × 10-8 cm2/s in the absence of annexin 5, respectively. The diffusion coefficients of β-BODIPY HPC and RyR2 in the presence of 1 μM annexin 5 were 2.4 × 10-10 cm2/s and 2.6 × 10-10 cm 2/s, respectively. Overall, 1 μM annexin 5 decreases the lateral diffusion coefficient 100-500 fold. Regarding RyR2, annexin 5 has little effect on function and can be used to immobilize RyR2 in a lipid bilayer system. © 2005 The Surface Science Society of Japan.