Plasma membrane calcium channels in human carcinoma A431 cells are functionally coupled to inositol 1,4,5-trisphosphate receptor-phosphatidylinositol 4,5-bisphosphate complexes.

Abstract

In most nonexcitable cells, calcium (Ca(2+)) release from inositol 1,4,5-trisphosphate (InsP(3))-sensitive intracellular Ca(2+) stores is coupled to Ca(2+) influx (calcium release-activated channels (I(CRAC))) pathway. Despite intense investigation, the molecular identity of I(CRAC) and the mechanism of its activation remain poorly understood. InsP(3)-dependent miniature calcium channels (I(min)) display functional properties characteristic for I(CRAC). Here we used patch clamp recordings of I(min) channels in human carcinoma A431 cells to demonstrate that I(min) activity was greatly enchanced in the presence of anti-phosphatidylinositol 4, 5-bisphosphate antibody (PIP(2)Ab) and diminished in the presence of PIP(2). Anti-PIP(2) antibody induced a greater than 6-fold increase in I(min) sensitivity for InsP(3) activation and an almost 4-fold change in I(min) maximal open probability. The addition of exogenous PIP(2) vesicles to the cytosolic surface of inside-out patches inhibited I(min) activity. These results lead us to propose an existence of a Ca(2+) influx pathway in nonexcitable cells activated via direct conformational coupling with a selected population of InsP(3) receptors, located just underneath the plasma membrane and coupled to PIP(2). The described pathway provides for a highly compartmentalized Ca(2+) influx and intracellular Ca(2+) store refilling mechanism.

• Authors: E Kaznacheyeva, A Zubov, A Nikolaev, V Alexeenko, I Bezprozvanny, G N Mozhayeva
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 275 Issue 7 Pg. 4561-4 (Feb 18 2000) ISSN: 0021-9258 [Print] United States
• PMID: 10671480 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Calcium Channels
• ITPR1 protein, human
• Inositol 1,4,5-Trisphosphate Receptors
• Phosphatidylinositol 4,5-Diphosphate
• Receptors, Cytoplasmic and Nuclear

Topics

• Calcium Channels (metabolism)
• Cell Membrane (metabolism)
• Humans
• Inositol 1,4,5-Trisphosphate Receptors
• Phosphatidylinositol 4,5-Diphosphate (immunology, metabolism)
• Receptors, Cytoplasmic and Nuclear (metabolism)
• Tumor Cells, Cultured