SBA — Single Best Answer · Review
Question 497
Endocrinology → General
Classification
Question
SSBAQuestion Header
A steroid hormone enters a target cell and binds its intracellular receptor. Which event is associated with activation of this receptor complex?
Question Stem
Select the single best answer.
Options
A
Activation of a seven-transmembrane receptor
B
Generation of cAMP by membrane-bound adenyl cyclase
C
Binding of the hormone to an extracellular glycoprotein receptor
D
Activation of a cell-surface guanylyl cyclase receptor
E
Displacement of HSP-90 followed by interaction of the activated complex with nuclear DNA
Explanation
Steroid hormones act through intracellular receptors. Hormone binding is associated with displacement of HSP-90 from the receptor, after which the activated hormone-receptor complex can interact with nuclear DNA and alter gene expression.
Option Validity
A) Seven-transmembrane receptors are cell-surface receptors used by hormones such as oxytocin and the gonadotrophins.
B) Adenyl cyclase and cAMP are components of a membrane-receptor second-messenger pathway rather than the steroid receptor mechanism described.
C) Steroid hormones act through intracellular rather than extracellular glycoprotein receptors.
D) Guanylyl cyclase-linked receptors are associated with natriuretic peptides rather than steroid-hormone signalling.
Further Reading
Saxena, MRCOG-1 Basic Sciences, Endocrinology: Mechanism of Action of Hormones, pp. 301–302.