Using patch clamp technique, we investigated the influence of anti-phosphatidylinositol-4,5-bisphosphate antibody (PIP2Ab) and phosphatidylinositol-4,5-bisphosphate (PIP2) on the activity of inositol-1,4,5-trisphosphate (IP3)-dependent miniature calcium channels (Imin) in plasma membrane of human carcinoma A431 cells. We demonstrate here that Imin activity is greatly enhanced in the presence PIP2Ab and diminished in the presence of PIP2. Anti-PIP2 antibodies induce more than a 6-fold increase in Imin sensitivity to IP3 activation and almost 4-fold change in Imin maximal open probability. We further demonstrated the synergism in activation of Imin by extracellular UTP and intracellular IP3. UTP receptor stimulation of PLC leads to ane increase in Imin sensitivity to IP3 as well to anti-PIP2 antibody. Based on these and previous data, we concluded that Imin/IP3R complex exists, and complex activation is modulated by PIP2. The activation of endogenous PLC and, consequently, the decrease of PIP2 level induced by Ca2+-mobilizing agonist diminish the inhibitory effect of PIP2 on Imin/IP3R complex and increase the ability of IP3 to activate Imin.
|Original language||English (US)|
|Number of pages||9|
|State||Published - Jan 1 2002|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology