Article Abstract:
Dopamine is a catecholamine neurotransmitter produced by the brain which affects the stimulation of nerves. Alteration in the number or activity of the cell receptors that bind dopamine is thought to be involved in diseases such as Parkinson's disease and schizophrenia. Drugs that have an effect on the dopamine receptors are given to patients with these diseases. The physiological effects of dopamine occur by its binding with two types of receptors: D1 receptors, which stimulate a second enzyme known as adenylyl cyclase; and D2 receptors, which inhibit adenylyl cyclase. These receptors are G protein-coupled receptors, receptors which bind G proteins. The receptors act as a bridge, sending a message inside the cell from a signal generated by the binding of a substance such as dopamine to a receptor on the cell surface. The enzyme adenylyl cyclase stimulates the activation of the cell. The authors report that the gene encoding a dopamine D1 receptor in humans has been isolated and characterized. The D2 receptor gene had already been isolated and characterized. The protein that is encoded by the gene is similar to that of other G protein-coupled receptors, and encodes a region that spans the cell membrane seven times. When the protein that is encoded by the gene was expressed in cells, the receptor was functional. It bound dopamine and stimulated the activity of adenylyl cyclase. It is thought that other subtypes of the D1 dopamine receptor may exist. The cloning of this gene will allow for further research so that the function of this gene, and how it is activated and regulated in both normal and disease states, can be understood. (Consumer Summary produced by Reliance Medical Information, Inc.)
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Article Abstract:
Dopamine is a neurotransmitter (a chemical which transmits messages between nerve cells), and it is produced by the brain. Abnormalities in the binding of dopamine to its receptors on cells are thought to occur in diseases such as schizophrenia and Parkinson's disease. Drugs that have effects on the dopamine receptors are given to patients with these diseases. The physiological effects of dopamine occur when it binds to two types of receptors: D1 receptors, which stimulate an enzyme known as adenylyl cyclase; and D2 receptors, which inhibit adenylyl cyclase. These receptors convey a message into the cell; the message is generated by the binding of a substance such as dopamine to a receptor on the cell surface. The D1 receptors mediate some behavioral responses, while D2 receptors regulate the growth and maturation of nerve cells. The gene encoding the D2 receptor has previously been isolated and characterized. The isolation and characterization of the gene encoding a dopamine D1 receptor in humans and rats is now reported. When the protein that is encoded by the gene was expressed in cells, the receptor was functional. It bound an antagonist of dopamine and stimulated the activity of adenylyl cyclase. The gene is active in various areas of the brain, especially the basal ganglia. The cloning of this gene will allow further research to be done to understand the function of this gene and how it is activated and regulated in both normal and disease states. (Consumer Summary produced by Reliance Medical Information, Inc.)
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Article Abstract:
Dopamine is a neurotransmitter produced by the brain which affects the stimulation of nerves. Defective binding of dopamine to its cell receptors may be an important aspect of diseases such as Parkinson's disease and schizophrenia, and perhaps drug addiction and alcoholism. Drugs that exert effects upon the dopamine receptors are given to patients with these diseases. The receptors are classified as G protein-coupled receptors, receptors which bind G proteins. There are two types of dopamine receptors, D1 and D2. The D1 receptors regulate the growth and maturation of nerve cells, influence some behavioral responses, and modify events caused by the D2 receptors. The gene encoding a dopamine D1 receptor in humans has been isolated and characterized. It is located on chromosome 5, near two other G protein receptors. When the protein that is encoded by the gene was expressed in cells, the receptor was functional. It bound an antagonist of dopamine and stimulated the activity of the enzyme adenylyl cyclase. The gene was found to be expressed in areas of the brain such as the frontal cortex and hypothalamus. The identification of the gene and its location on chromosome 5 allows for further study to see if individuals with abnormalities of this receptor have a particular disease state. (Consumer Summary produced by Reliance Medical Information, Inc.)
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