This set of Molecular Endocrinology Multiple Choice Questions & Answers (MCQs) focuses on “Receptors”.
1. Which among the following receptors act as transcription factors?
a) Receptors for steroid and thyroid hormones
b) Receptors of insulin
c) Low-density lipoprotein receptors
d) High-density lipoprotein receptors
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Explanation: In endocrinology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein which, by binding to a specific DNA sequence, controls the rate of transcription of genetic information from DNA to messenger RNA. Some receptors are found inside the cell (e.g., steroid and thyroid hormone receptors) and they also serve as transcription factors.
2. Which among the following receptors carry out receptor mediated endocytosis?
a) High-density lipoprotein receptors
b) Low-density lipoprotein receptors
c) Receptors of insulin
d) Receptors for steroid and thyroid hormones
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Explanation: On the cell surface, receptors like low-density lipoprotein receptors are found. Via a mechanism referred to as receptor-mediated endocytosis, they mainly act to transport their ligands into the cell. Low-density receptors of lipoproteins pick up and transmits LDLs circulating in the bloodstream into the cell.
3. Which among the following cell-surface receptors is a Ligand-gated ion channel?
a) Receptors for insulin
b) Receptors for activins
c) Nicotinic acetylcholine receptors
d) Atrial natriuretic factor receptor
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Explanation: It is possible to classify cell surface receptors according to the molecular mechanisms by which they achieve signaling. The Ligand-gated ion channels containing nicotinic acetylcholine receptors are one of them.
4. Most hormones bind to proteins that are different from receptors.
a) True
b) False
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Explanation: Often hormones bind to proteins that are different from receptors. This is because the binding proteins do not activate the mechanisms of signaling that mediate the activity of hormones. Hormones activate target cells by diffusing a receptor protein into the cytoplasm of the cell via the plasma membrane of the target cells (lipid-soluble hormones) or by binding a particular receptor protein to the cell membrane of the target cell (water-soluble proteins).
5. Hormones circulate in plasma at very high concentrations.
a) True
b) False
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Explanation: Hormones circulate in plasma at very small concentrations. It is characterized by the binding relationship between a hormone and its receptor. For good health, plasma concentrations of hormones must be carefully controlled.
6. Which among the following is a Receptor tyrosine kinase?
a) Receptors for insulin
b) Receptors for activins
c) Nicotinic acetylcholine receptors
d) Atrial natriuretic factor receptor
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Explanation: Receptor tyrosine kinases include receptors for insulin and insulin-like growth factor 1. These receptors are bifunctional molecules that can bind hormones and, by acting as ion channels or enzymes, they can also function as effectors.
7. Which among the following is a G protein–coupled receptor?
a) Muscarinic cholinergic agents
b) Receptors for insulin
c) Nicotinic acetylcholine receptors
d) Atrial natriuretic factor receptor
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Explanation: Muscarinic cholinergic agents is an example of G protein-coupled receptor. GPCRs are an evolutionarily conserved gene superfamily with members from yeast to mammals in all eukaryotes. Muscarinic agonists, especially in the GI tract, urinary bladder and the eye, are most widely used when it is desirable to improve smooth muscle tone.
8. Which among the following is a cytokine receptor?
a) Receptors for insulin
b) Receptors for activins
c) Atrial natriuretic factor receptor
d) Prolactin
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Explanation: Prolactin is a hormone formed by the pituitary gland that sits at the bottom of the brain. Prolactin is an example for a cytokine receptor. In order to activate downstream signaling, cytokine receptors recruit cytosolic tyrosine kinases (e.g., Janus family tyrosine kinases [JAKs]) as effectors.
9. Which among the following is an example of the receptor that binds with lower affinity?
a) Insulin Receptor
b) Receptors for activins
c) Atrial natriuretic factor receptor
d) Prolactin
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Explanation: Insulin is an anabolic peptide hormone secreted via a receptor located in the membrane of target cells by the b cells of the pancreas. Certain receptors bind to hormones with lower affinity. For instance, with about 100 times lower affinity, the insulin receptor binds insulin-like growth factors (IGFs) than it binds insulin.
10. Which among the following receptors exhibit a property known as ‘specificity spillover’?
a) Insulin receptor
b) Thyrotropin receptor
c) Activin Receptor
d) Leptin
View Answer
Explanation: The receptor for thyrotropin binds to human chorionic gonadotropin with a lower affinity than thyrotropin. This occurrence has been referred to as specificity spillover, and this gives an explanation of many pathological disorders
Sanfoundry Global Education & Learning Series – Molecular Endocrinology.
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