This set of Molecular Endocrinology Multiple Choice Questions & Answers (MCQs) focuses on “Receptors that Signal through Associated Tyrosine Kinases”.
1. Which are the three hormones that act as ligands in the receptor cytokine family?
a) GH, Prolactin and Leptin
b) FSH, Prolactin and Leptin
c) GH, Adrenaline and Leptin
d) GH, LH and FSH
View Answer
Explanation: There are various roles for more than 40 ligands that bind to members of the cytokine receptor family. Three of these ligands are hormones and they are GH, Prolactin and Leptin. By adding unique membrane receptors, cytokines work on their target cells.
2. Which among the following ligands regulate hematopoiesis or the immune response?
a) GH
b) Erythropoietin
c) Prolactin
d) Leptin
View Answer
Explanation: Hematopoiesis or immune reaction was regulated by certain ligands of cytokine receptors, such as erythropoietin. Many interleukins and interferons – alpha, – β and – γ play the same function. Erythropoietin (EPO) is a hormone released predominantly by the kidneys, with the liver producing small quantities.
3. What is the name of the disease that is caused by autosomal recessive mutations of the GH receptor?
a) Morbid obesity
b) Phenylketonuria
c) Laron dwarfism
d) Maple Syrup Urine disease
View Answer
Explanation: It is possible to trace a variety of genetic disorders due to mutations in cytokine receptors. Laron dwarfism, for instance, is caused by GH receptor autosomal recessive mutations. Laron syndrome is a disorder that arises when growth hormone cannot be used by the body.
4. Members of the cytokine family of receptors resemble receptor tyrosine kinases in their mechanism of action.
a) True
b) False
View Answer
Explanation: In their mechanism of action, members of the cytokine family of receptors mimic receptor tyrosine kinases, with one major exception. Enzymatic function occurs in an enzyme that interacts with the cytokine receptor rather than having a tyrosine kinase that is intrinsic to the receptor.
5. In extracellular and cytoplasmic domains, members of the cytokine family of receptors share homology.
a) True
b) False
View Answer
Explanation: In the extracellular and cytoplasmic regions, members of the cytokine family of receptors do share a homology. It is believed that certain cytokine receptors, including GH, prolactin, and leptin receptors, are composed of dimers from a single subunit of receptors.
6. What disease is caused by the autosomal recessive mutations of the leptin receptor?
a) Laron dwarfism
b) Morbid obesity
c) Phenylketonuria
d) Maple Syrup Urine disease
View Answer
Explanation: A variety of genetic conditions can be traced due to cytokine receptor deficiencies. Morbid obesity can be caused by autosomal recessive leptin receptor mutations. If a person is 100 pounds above his or her ideal body weight, a person is considered morbidly obese.
7. In order to serve as a molecular interface between the neuroimmune and endocrine systems, which group subunit binds to the leukemia inhibitory factor?
a) Gp130
b) Alpha Regulatory
c) Beta Regulatory
d) Gp77
View Answer
Explanation: The leukemia inhibitory factor binds to a receptor consisting of the gp130 subunit and the leukemia inhibitory factor receptor’s β-subunit. This is a multi-function pleiotropic cytokine which seems to act as a molecular interface between the neuroimmune and endocrine systems.
8. What happens when the gp130 subunit and the leukemia inhibitory factor receptor β-subunit is combined with a ciliary neurotrophic factor’s receptor subunit?
a) Changes the conformation of ciliary neurotrophic factor
b) Activates ciliary neurotrophic factor
c) Deactivates ciliary neurotrophic factor
d) A preference for ciliary neurotrophic factor developed
View Answer
Explanation: When paired with a ciliary neurotrophic factor’s receptor subunit, the gp130 subunit and the leukemia inhibitory factor receptor’s β-subunit show a preference for the ciliary neurotrophic factor. It is a trophic factor that is also a potent appetite suppressor for motor neurons in the ciliary ganglia and spinal cord.
9. Which group subunit is bound to interleukin 6 in order to show a preference for IL-6?
a) Gp130
b) Gp180
c) Gp751
d) Gp190
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Explanation: The receptor displays a preference for IL-6, if two gp130 subunits are paired with an interleukin 6 (IL-6) receptor subunit. With additional anti-inflammatory properties, this is an inducer of the acute phase reaction.
10. To which enzymes does the members of the cytokine family of receptors bind to exhibit the enzyme activity?
a) Ligase
b) Janus family of tyrosine kinases
c) Aromatases
d) Pectin receptor kinases
View Answer
Explanation: Members of the receptor cytokine family do not themselves exhibit enzymatic action. Instead, they bind members in a proline-rich region of the Janus family of tyrosine kinases (JAKs). Janus Kinases (JAKs) are enzymes that phosphorylate residues of tyrosine on target proteins that primarily function as a signal transducer in the signalling pathway of JAK-STAT.
11. Which are the four known Janus family of tyrosine kinases?
a) JAK1, JAK2, JAK3, and TYK2
b) JAK1, JAK2, JAK3, and JAK4
c) JAK1, JAK2, JAK3, and TYK7
d) JAK1, JAK2, JAK3, and JAK7
View Answer
Explanation: One of ten recognized families of non-receptor tyrosine kinases is the Janus kinase (Jak) family. Four JAKs, designated JAK1, JAK2, JAK3, and TYK2, are known. The JAKs mix and match their subunits, like the cytokine receptors themselves.
12. Cite an example for a cytokine receptor that shows preference for a single JAK?
a) GH
b) Interferon-γ
c) IL-2
d) IL-9
View Answer
Explanation: Some cytokine receptors display a clear preference for a single JAK, others require two separate JAKs, and others seem to activate several members of the JAK family. GH, prolactin, and leptin preferentially activate JAK2.
13. In which among the following ligands does the JAK appear to be constitutively associated with the cytokine receptor?
a) Prolactin
b) GH Receptor
c) Leptin Receptor
d) SAS Receptor
View Answer
The required JAK family member or members are activated by the binding of a ligand to a cytokine receptor. The JAKs seem to be constitutively correlated with the cytokine receptor in certain cases, such as prolactin, and ligand binding enhances their activity.
14. What is the basic requirement for the activation of JAK?
a) Receptor oligomerization
b) Ligand oligomerization
c) Enzyme catalyst
d) Catalyst oligomerization
View Answer
Explanation: Activation of JAKs includes oligomerization of receptors. This is likely achieved to get two or more JAKs close enough to the activating tyrosine in the kinase domain to trans phosphorylate each other.
15. What is the process that causes a conformational change in the receptor?
a) Transphosphorylation
b) Trans acetylation
c) Trans methylation
d) Trans carboxylation
View Answer
Explanation: A conformational alteration that reveals the ATP-binding or substrate-binding site, or both, is thought to be caused by transphosphorylation. And it is believed that activation releases an autoinhibitory domain.
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