Interaction of protein phosphatase inhibitors with membrane lipids assessed by surface plasmon resonance based binding technique

• Interactions of protein phosphatase inhibitors with liposomes were studied.
• Interactions are assessed by surface plasmon resonance based binding technique.
• The binding affinity of inhibitors depends on the lipid composition of liposomes.
• At 37 °C inhibitors are retained in the liposomes and dissociate slowly.
• The inhibitor-membrane lipid interaction influences phosphatase inhibition in cells.

The interaction of okadaic acid (OA), tautomycin (TM), microcystin-LR (MC-LR), cantharidin (CA), epigallocatechin-gallate (EGCG) and cyclosporin A (CsA), inhibitors of protein phosphatases, with liposome covered surfaces prepared from the lipid extracts of bovine brain, heart and liver was investigated by surface plasmon resonance (SPR) based binding technique. The SPR sensorgrams indicated reversible association or partial intercalation of the inhibitors with liposomes at 20 °C or 37 °C, respectively. Distinct lipid composition specificities were reflected in different saturation values of inhibitor binding in a decreasing order of liver > heart >> brain lipids. Assaying the effect of OA, TM, MC-LR, CA and EGCG on the activity of protein phosphatases in neuroblastoma B50, cardiomyoblast H9C2 and hepatocarcinoma HepG2 cells implied that the cell type specific association of phosphatase inhibitors with membrane lipids may influence their inhibitory potencies exerted on intact cells.

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