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Putative calcium channel molecular weight determination by target size analysis.
Naunyn-Schmiedeberg'S Archives of Pharmacology
|August 1, 1983
Summary
This study determined the molecular weight of guinea-pig brain calcium channels using target size analysis. The calcium channel molecular weight was found to be 185,000, validated against benzodiazepine receptors.
Area of Science:
- Neuroscience
- Biochemistry
- Molecular Pharmacology
Background:
- Calcium channels are crucial for neuronal function.
- Nimodipine is a known calcium channel blocker.
- Target size analysis is a method to determine the molecular weight of proteins in situ.
Purpose of the Study:
- To determine the molecular weight of the putative calcium channel in guinea-pig brain membranes.
- To validate the target size analysis method using benzodiazepine receptors as an internal control.
Main Methods:
- Guinea-pig brain membranes were labeled with [3H]-nimodipine.
- Membranes were irradiated with 10 MeV electrons at low temperatures (153-173 K).
- Binding site density was measured, and target size theory was applied.
Main Results:
- Irradiation reduced [3H]-nimodipine binding site density without altering the equilibrium dissociation constant.
- Target size analysis yielded a molecular weight of 185,000 for the calcium channel.
- Benzodiazepine receptors had a molecular weight of 76,000, consistent with previous studies.
Conclusions:
- The molecular weight of the putative calcium channel in guinea-pig brain membranes is 185,000.
- Target size analysis is a reliable method for determining the molecular weight of membrane-bound receptors.