The binding of cytochalasin B (CB) to human platelets and to isolated platelet cytosol and membranes has been analyzed with [3H]CB. High-and low affinity classes of saturable binding sites were associated with intact platelets. Binding at very low concentrations of CB (i.e., high-affinity binding) w
Cellular binding of 3H-cytochalasin B
✍ Scribed by E. Mayhew; G. Poste; M. Cowden; N. Tolson; D. Maslow
- Publisher
- John Wiley and Sons
- Year
- 1974
- Tongue
- English
- Weight
- 847 KB
- Volume
- 84
- Category
- Article
- ISSN
- 0021-9541
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✦ Synopsis
Abstract
The binding of tritium‐labelled cytochalasin B (^3^H‐CB) to a variety of mammalian cells was investigated. Binding studies revealed near‐equilibrium binding of ^3^H‐CB within 5 to 10 minutes, but the equilibrium level was influenced by ^3^H‐CB concentration. Binding kinetics revealed strong temperature dependence. Rapid release of up to 70% of cell‐bound ^3^H‐CB molecules occurred when cells were washed and returned to fresh medium without CB. The remaining 30% of cell‐bound ^3^H‐CB molecules dissociated more slowly. Equilibrium binding studies on a variety of diploid, heteroploid and transformed cells treated with 1 μg/ml ^3^H‐CB revealed between 1.7 X 10^7^ to 5.3 X 10^7^ ^3^H‐CB binding sites per cell. Cellular binding of ^3^H‐CB was not affected by inhibition of cellular energy metabolism, RNA or protein synthesis. Modification of the cell surface by proteases, neuraminidase, hyaluronidase, ribonuclease, or occupation of cell surface saccharide residues by a variety of plant lectins did not significantly alter the pattern of ^3^H‐CB binding. Surface pressure measurements on CB‐treated lipid monolayers indicated that CB can interact with lipid molecules. The partition of CB in hydrophobic lipid regions of cell membrane systems as a possible mechanism of cellular binding of CB is discussed. Fractionation of ^3^H‐CB‐treated cells revealed binding of ^3^H‐CB to both the plasma membrane and by intracellular membranes.
📜 SIMILAR VOLUMES
intact human platelets bind cytochalasin B (CB) with a capacity of 100-120 p mols CBimg protein or approximately 7 x lo4 rnoleculeslcell and dissociation constants (KD) ranging from 2 x 10" to lo6 M. Up to 85% of this saturable binding is displaced by 'lo+ M cytochalasin E (CE). This CE-sensitive bi
## Abstract To study the molecular basis of changes in sugar uptake rate in cultured mouse fibroblasts with different physiological states, we have measured the high affinity binding of [^3^H] cytochalasin B, a potent sugar transport inhibitor, to actively growing and contact inhibited Balb/3T3 cel
## Abstract Cytochalasin B (CB) was able to compete with tritiated cytochalasin D (^3H^‐CD) for binding sites in HEp‐2 cells. The pattern of inhibition suggested that CB associates with a low affinity class of CD binding sites. Glucose and maltose did not inhibit binding of ^3^H‐CD to isolated HEp‐