Abstract
The modulation of P-glycoprotein's (Pgp) ATPase activity and its ability to regulate swelling-activated 125I efflux, by PKC α and PKC ɛ, was examined in insect cells. Recombinant baculovirus was used to express human Pgp in Sf9 cells and Pgp was also co-expressed with either PKC α or PKC ɛ. ATPase assays showed the enzyme activity of Pgp to be elevated during co-expression with the Ca2+ dependent isoform PKC α, but not with the Ca2+ independent variant PKC ɛ. Furthermore, neither isoform, when co-expressed with Pgp, altered the swelling-activated efflux of 125I from Sf9 cells. However, in cells co-expressing Pgp/PKC (α or ɛ), pre-treatment with the phorbol ester TPA significantly reduced the swelling-activated 125I efflux with both PKC isoforms. Our results suggest that phosphorylation with the Ca2+ independent variant PKC ɛ does not regulate the ATPase activity of Pgp and that stimulation of PKC with TPA alters the swelling-activated efflux of anions from insect cells expressing Pgp.
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Received: 8 March 2000 / Accepted: 5 June 2000
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Idriss, H., Urquidi, V. & Basavappa, S. Selective modulation of P-glycoprotein's ATPase and anion efflux regulation activities with PKC α and PKC ɛ in Sf9 cells. Cancer Chemother Pharmacol 46, 287–292 (2000). https://doi.org/10.1007/s002800000172
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DOI: https://doi.org/10.1007/s002800000172