Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

Ca2+ Entry through Plasma Membrane IP3 Receptors

Olivier Dellis, Skarlatos G. Dedos, Stephen C. Tovey, Taufiq-Ur-Rahman, Stefan J. Dubel and Colin W. Taylor
Science
New Series, Vol. 313, No. 5784 (Jul. 14, 2006), pp. 229-233
Stable URL: http://www.jstor.org/stable/3846704
Page Count: 5
  • More info
  • Cite this Item
Ca2+ Entry through Plasma Membrane IP3 Receptors
Preview not available

Abstract

Inositol 1,4,5-trisphosphate receptors ($IP_{3}Rs$) release calcium ions, Ca2+, from intracellular stores, but their roles in mediating Ca2+ entry are unclear. IP3 stimulated opening of very few ($1.9 \pm 0.2$ per cell) Ca2+-permeable channels in whole-cell patch-clamp recording of DT40 chicken or mouse B cells. Activation of the B cell receptor (BCR) in perforated-patch recordings evoked the same response. IP3 failed to stimulate intracellular or plasma membrane (PM) channels in cells lacking $IP_{3}R$. Expression of $IP_{3}R$ restored both responses. Mutations within the pore affected the conductances of IP3-activated PM and intracellular channels similarly. An impermeant pore mutant abolished BCR-evoked Ca2+ signals, and PM $IP_{3}Rs$ were undetectable. After introduction of an α-bungarotoxin binding site near the pore, PM $IP_{3}Rs$ were modulated by extracellular α-bungarotoxin. $IP_{3}Rs$ are unusual among endoplasmic reticulum proteins in being also functionally expressed at the PM, where very few $IP_{3}Rs$ contribute substantially to the Ca2+ entry evoked by the BCR.

Page Thumbnails

  • Thumbnail: Page 
229
    229
  • Thumbnail: Page 
230
    230
  • Thumbnail: Page 
231
    231
  • Thumbnail: Page 
232
    232
  • Thumbnail: Page 
233
    233