Actin-dependent organelle movement in squid axoplasm.
Studies of organelle movement in axoplasm extruded from the squid giant axon have led to the basic discoveries of microtubule-dependent organelle motility and the characterization of the microtubule-based motor proteins kinesin and cytoplasmic dynein. Rapid organelle movement in higher animal cells, especially in neurons, is considered to be microtubule-based. The role of actin filaments, which are also abundant in axonal cytoplasm, has remained unclear. The inhibition of organelle movement in axoplasm by actin-binding proteins such as DNase I, gelsolin and synapsin I has been attributed to their ability to disorganize the microtubule domains where most of the actin-filaments are located. Here we provide evidence of a new type of organelle movement in squid axoplasm which is independent of both microtubules and microtubule-based motors. This movement is ATP-dependent, unidirectional, actin-dependent, and probably generated by a myosin-like motor. These results demonstrate that an actomyosin-like mechanism can be directly involved in the generation of rapid organelle transport in nerve cells.
Kuznetsov
S A
SA
Marine Biological Laboratory, Woods Hole, Massachusetts 02543.
Langford
G M
GM
Weiss
D G
DG
D008841:Actin Cytoskeleton / Q000187:drug effects / Q000502:physiology; D000199:Actins / Q000187:drug effects / Q000502:physiology*; D000266:Adenylyl Imidodiphosphate / Q000494:pharmacology; D000818:Animals; D001081:Apyrase / Q000494:pharmacology; D001369:Axons / Q000502:physiology*; D003571:Cytochalasin B / Q000494:pharmacology; D049832:Decapodiformes; D004492:Edetic Acid / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D006593:Hexokinase / Q000494:pharmacology; D009068:Movement / Q000187:drug effects / Q000502:physiology*; D015739:Nocodazole / Q000494:pharmacology; D015388:Organelles / Q000502:physiology*; D014638:Vanadates / Q000494:pharmacology
D000199:Actins; D000266:Adenylyl Imidodiphosphate; D003571:Cytochalasin B; D014638:Vanadates; D004533:Egtazic Acid; D004492:Edetic Acid; D006593:Hexokinase; D001081:Apyrase; D015739:Nocodazole