Transmembrane signaling through phospholipase C in human cortical membranes |
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Authors: | Michael A Wallace Enrique Claro |
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Institution: | (1) Department of Biochemistry, University of Tennessee, Memphis, 858 Madison Avenue, 38163 Memphis, Tennessee;(2) Present address: Departamento de Bioquimica y Biologia Molecular Facultad de Medicina, Universidad Autonoma de Barcelona, 08193 Bellaterra, Barcelona, Spain |
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Abstract: | Stimulation of phosphoinositide-specific phospholipase C (PLC) by carbachol, dopamine and serotonin was measured by supplying exogenous 3H]phosphatidylinositol 4,5-bisphosphate to membranes prepared from human cortex dissected and frozen at autopsy. Subjects with Alzheimer's disease, Parkinson's disease or schizophrenia were compared to age-matched controls with no known neurological disorders. Stimulation of PLC by the neurotransmitters was dependent on the presence of GTPS. Carbachol elicited the greatest stimulations of PLC followed by serotonin and then dopamine. The maximal stimulations of PLC evoked by a neurotransmitter were similar for the various categories of subjects except in Parkinson's patients, where dopamine failed to stimulate PLC beyond the activity attained with carbachol. In the presence of carbachol, the sensitivity of PLC to GTPS was significantly increased in Alzheimer's membranes, but not in age-matched controls or Parkinson's. Overall, the experiments demonstrate the feasibility for using the exogenous substrate assay to study the functionality of the phosphoinositide transmembrane signaling system in human brain.Abbreviations PLC
phospholipase C
- GTPS
guanosine 3-O-thiotriphosphate
- Gpp(NH)p
5-guanylyl-imidodiphosphate
- DA
dopamine
- CCh
earbachol
- 5-HT
serotonin
- PIP2
phosphatidylinositol 4,5-bisphosphate
- PIP
phosphatidylinositol 4-bisphosphate |
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Keywords: | Phospholipase C dopamine serotonin carbachol Parkinson's disease Alzheimer's disease schizophrenia G proteins |
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