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Mu-opioid receptor is associated with phosphatase activity
Biochemical and Biophysical Research Communications
|October 30, 1986
Summary
This study shows that mu opioid receptors from bovine brain possess phosphatase activity. This enzymatic function, distinct from alkaline phosphatase, suggests a novel role for opioid receptors.
Area of Science:
- Biochemistry
- Neuroscience
- Enzymology
Background:
- Mu opioid receptors are primarily known for their role in pain modulation and neurotransmission.
- Enzymatic activities associated with G protein-coupled receptors are increasingly being discovered.
Purpose of the Study:
- To investigate potential enzymatic activities of purified mu opioid receptors.
- To characterize the phosphatase activity observed in the opioid receptor preparation.
Main Methods:
- Purification of mu opioid receptor from bovine brain.
- Assay of p-nitrophenylphosphate hydrolysis.
- Determination of pH optimum, Km, and ion stimulation.
- Molecular weight analysis and antibody absorption tests.
Main Results:
- Purified mu opioid receptor preparation exhibited phosphatase activity.
- The activity showed a pH optimum of 9.0, a Km of 9.0 microM, and was stimulated by Mn++ and Mg++.
- The enzymatic activity was associated with a 60,000 molecular weight protein and was not recognized by alkaline phosphatase antibodies.
Conclusions:
- The observed phosphatase activity is intrinsic to the mu opioid receptor, not a contaminant.
- This is the first demonstration of enzymatic activity directly associated with an opioid receptor.
- Opioid receptors may possess novel functions beyond signal transduction.