کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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2192448 | 1097891 | 2006 | 9 صفحه PDF | دانلود رایگان |

In neonatal rat cardiomyocytes, phosphatidylinositol(4,5)bisphosphate (PIP2) is a precursor of second messengers, a stabilizer of ion channels and exchangers, an anchor point for the cytoskeleton and, in addition, can serve as a signaling molecule in its own right. We examined the possibility that sarcolemmal PIP2 exists in different pools and that only one of these provides the substrate for α1-adrenergic receptor activated phospholipase C (PLC). Membranes were separated on the basis of buoyant density, and the light lipid raft fractions were further separated into caveolae and non-caveolar rafts using immunoprecipitation. PIP2 was principally located in the light lipid raft fractions and was equally distributed between caveolae and non-caveolar membranes. Heavier membrane fractions also contained some PIP2. Addition of the α1-adrenergic receptor agonist phenylephrine (50 μM) caused reductions in PIP2, but only in caveolae. PIP2 in other fractions was unaffected. In agreement with this, PLCβ1 and, to a lesser extent, Gαq were concentrated in this fraction. PLCβ3 was primarily observed in heavier membranes. We conclude that PIP2 in cardiomyocyte sarcolemma is compartmentalized and that α1-adrenergic receptor signaling is localized to caveolae.
Journal: Journal of Molecular and Cellular Cardiology - Volume 41, Issue 1, July 2006, Pages 17–25