Single microtubules from squid axoplasm support bidirectional movement of organelles

Bruce J. Schnapp, Ronald D. Vale, Michael P. Sheetz, Thomas S. Reese

Research output: Contribution to journalArticlepeer-review

218 Scopus citations


Single filaments, dissociated from the extruded axoplasm of the squid giant axon and visualized by videoenhanced differential interference contrast microscopy, transport organelles bidirectionally. Organelles moving in the same or opposite directions along the same filament can pass each other without colliding, indicating that each transport filament has several tracks for organelle movement. In order to characterize transport filaments, organelle movements were first examined by video microscopy, and then the same filaments were examined by electron microscopy after rapid-freezing, freeze-drying, and rotaryshadowing. Transport filaments that supported bidirectional movement of organelles are 22 nm to 27 nm in diameter and have a substructure indicative of a single microtubule. Immunofluorescence showed that virtually all transport filaments contain tubulin. These results show that single microtubules can serve as a substratum for organelle movement, and suggest that an interaction between organelles and microtubules is the basis of fast axonal transport.

Original languageEnglish (US)
Pages (from-to)455-462
Number of pages8
Issue number2
StatePublished - Feb 1985
Externally publishedYes

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology


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