Inhibition of CaT1 channel activity by a noncompetitive IP3 antagonist

Academic Article


  • A newly cloned, human epithelial Ca2+ transport protein (CaT1) was expressed in Xenopus laevis oocytes, and its single channel characteristics were examined. The CaT1 channel shows a strong dependence upon hyperpolarizing voltages, being activated by very negative voltages. The probability of channel opening and mean open times increase substantially at more negative voltages in the range of -90 to -160 mV. In addition, CaT1 channel activity was markedly inhibited by micromolar levels of a noncompetitive antagonist of the IPa receptor originally isolated from a marine sponge, Xestospongin C. This inhibitory effect could be mediated indirectly via the binding of Xestospongin C to the inositol-trisphosphate (IP3) receptor or, alternatively, by a direct action on the CaT1 channel itself. Independent of its mechanism of action in inhibiting CaT1, Xestospongin C will provide a useful tool for elucidating the physiological role(s) of this novel epithelial Ca2+ channel. © 2001 Academic Press.
  • Authors

    Digital Object Identifier (doi)

    Author List

  • Vassilev PM; Peng JB; Johnson J; Hediger MA; Brown EM
  • Start Page

  • 145
  • End Page

  • 150
  • Volume

  • 280
  • Issue

  • 1