We have previously described the isolation of a mutant KB cell (Cyt 1 mutant) resistant to the cytotoxic effect of cytochalasin B (CB). The Cyt 1 mutant carries an altered form of beta-actin (beta'-actin) and lacks normal beta-actin (Toyama, S., and S. Toyama. 1984. Cell. 37:609-614). Increased resistance of the Cyt 1 mutant to CB in vivo is reflected in altered properties of beta'-actin in vit...

We have recently reported (3) that cytochalasin B, which disrupts microfilaments, and colchicine, which disrupts microtubules, interfered with the release of a-amylase from rat parotid tissue slices . Our observations on the effect of cytochalasin B on a-amylase release have been confirmed by Rifkin et al . (14) . Inhibitory actions of cytochalasin B or colchicine in several other systems have ...

The role of cytoskeletal microtubules and microfilaments in modulating cAMP generation in S49 lymphoma cells was investigated using the agents colchicine and cytochalasin B, respectively, which are known to disrupt these structures. A 1-hr pretreatment of S49 cells with 10 microM colchicine typically enhanced maximal isoproterenol-(beta-adrenergic receptor) stimulated cAMP accumulation by 100%,...

INTRODUCTION the addition of the drug . Concentrations of about 3 μg/ml were required to observe altered cell morphology. The possibility was considered that depolymerization of microfilaments-with a resulting change in cell shape and function--resulted from a rapid depletion of intracellular energy levels brought about by the inhibition of sugar transport . The effects of cytochalasin B and io...

Apical and basolateral endocytic pathways in polarised Caco-2 cells were investigated by following the uptake, recycling and transcytosis of the galactose-binding protein toxin ricin, as a membrane marker. Differences in the extent and kinetics of lectin uptake, recycling and transcytosis were observed at the apical and basolateral domains and altered with the age of the cell monolayer. Treatme...

The attachment of particle-bound IgG in a nonphagocytic system stimulates formation of a microfilament-rich, organelle-poor zone in the subjacent cytoplasm of human neutrophils. The attachment site is characterized by ruffling and invagination of the neutrophil membrane. Both IgG attachment and formation of the organelle-poor zone are inhibited by the microfilament inhibitor cytochalasin-B, but...

C YTOCHALASINS and phalloidins are two groups of small, naturally occurring organic molecules that bind to actin and alter its polymerization. They have been widely used to study the role of actin in biological processes and as models for actin-binding proteins. Functionally , cytochalasins resemble capping proteins, which block an end of actin filaments, nucleate polymerization, and shorten fi...

The mold metabolite cytochalasin B blocked transmission through the perfused superior cervical sympathetic ganglion of the cat. Acetylcholine injected close-arterially during block continued to excite the ganglion cells so that failure was presynaptic and, by inference, due to reduced output of acetylcholine from the preganglionic nerves. This blocking effect of cytochalasin was reduced by pyru...

Villin, a 95,000-dalton protein, is a major component of microvillus cores isolated from intestinal brush borders. In this study, we compared the Ca2+-dependent action of this protein on actin filaments with that of cytochalasin B, a fungal metabolite that binds to the "barbed" end of actin filaments and nuclei. We found that substoichiometric levels of villin inhibit actin filament elongation ...