Spatiotemporal fluctuations in fluorescence intensity of rhodamine phalloidin-labeled actin filaments.

ABSTRACT: Phalloidin (Ph) is widely used for fluorescent labeling of actin filaments. We observed ADP-actin filaments labeled with rhodamine phalloidin (RhPh) or Alexa488-Ph in vitro and discovered that the fluorescence intensities along the filaments showed a mottled pattern of bright and dark regions. Filaments labeled with substoichiometric RhPh exhibited more significant fluorescence inhomogeneities than those labeled with excess RhPh. Because the quantum yield of Alexa488 fluorescence is hardly affected by the environment, we concluded that the inhomogeneities arise from nonuniform Ph binding density rather than locally inhomogeneous quantum yield of the fluorophores. Simulations assuming random RhPh binding alone partially produced fluorescence inhomogeneities, but the degree of inhomogeneitie

SUBMITTER: Toshino K 

PROVIDER: S-EPMC12305204 | biostudies-literature | 2025 Jun

REPOSITORIES: biostudies-literature