Cytochalasin inhibition of hexone transport by platelets

Binding of cytochalasin B to platelets

“…Another possibility, however, is that this transporter is inhibited by the unsaturable component of CB binding. This hypothesis is attractive because our kinetic data were consistent with CB inhibition of diffusion through the lipid bilayer of the platelet membrane, affecting both facilitated and unfacilitated transport [8]. Lipid solubility might produce the unsaturable binding of CB to the membranes as well as disturb diffusion-dependent processes.…”

“…1). Since CE does not inhibit hexose transport by platelets, we would expect CEdisplaceable CB binding not to involve the hexose transporters [8].…”

“…This subclass may involve the platelet hexose transporter that CB inhibits by a mixed-type mechanism (Ki -0.8 pM) [8]. Another possibility, however, is that this transporter is inhibited by the unsaturable component of CB binding.…”

“…Platelets have been useful in studying this toxin because these cells manifest a variety of contractile functions, including shape change, aggregation, and clot retraction, all of which are suppressed by CB [5-71. Recently we have also shown that this compound interrupts platelet transport of D-galactose [8]. These effects are presumably mediated by CB binding to filamentous acting (F-actin) and to membrane structures involved with transport [9-111.…”

“…CB binding to muscle actin and to the hexose transporter of red cells has been well documented [9,10,12]. Binding of CB to bovine and human platelets also has been described, although the exact subcellular localization of the binding has remained uncertain [13][14][15].Our interest in CB binding to platelets stems from recent studies of CB inhibition of galactose transport by these cells [8]. Previously we had identified two kinetically distinct platelet transporters for D-galactose [16].…”