Question

Intracellular receptors are mostly what type?
(a)Cytoplasmic receptors
(b)Membrane receptors
(c)Nuclear receptors
(d)ER receptors

Answer 1

Hint: In the cytoplasm of the cell, internal receptors, also known as intracellular, are located and react to molecules of hydrophobic ligands that can pass across the plasma membrane.

Complete answer:
Receptors found within the cell rather than on its cell membrane are intracellular receptors. Thyroid and steroid hormones contain classic hormones that use intracellular receptors. The class of nuclear receptors in the cell nucleus and cytoplasm and the Inositol triphosphate receptor in the endoplasmic reticulum are examples. Intracellular second messengers such as inositol trisphosphate and extracellular lipophilic hormones such as steroid hormones are typically the ligands that bind to them. There are also intracellular receptors on certain intracrine peptide hormones.
They are specialized integral membrane proteins that enable the cell and extracellular space to communicate. Hormones, neurotransmitters, cytokines, growth factors, cell adhesion molecules, or nutrients may be extracellular molecules; they react with the receptor to cause changes in the cell's metabolism and operation. Ligand binding affects a cascading chemical transition through the cell membrane in the course of signal transduction.

Additional Information: Receptors that are embedded in the plasma membrane of cells are cell surface receptors (membrane receptors, transmembrane receptors). They function by obtaining (binding to) extracellular molecules for cell signaling. They are specialized integral membrane proteins that allow the cell and extracellular space to communicate.
Nuclear receptors are a class of proteins located within cells that are responsible for detecting steroid and thyroid hormones and many other molecules in the field of molecular biology.
A group of proteins located within cells is estrogen receptors (ERs). There are two groups of ERs: nuclear estrogen receptors (ER-alpha and ERβ), which are part of the intracellular receptor family, and membrane estrogen receptors (mERs) (GPER (GPR30), ER-X, and Gq-mER), which are mainly G protein-coupled receptors. They are receptors that are activated by the hormone estrogen. This article refers to the former (ER).
So, the correct answer is ‘cytoplasmic receptors’.

Note: There have been two models proposed to describe the mechanism of action of transmembrane receptors-
Dimerization: The dimerization model indicates that receptors reside in a monomeric shape prior to ligand binding. The monomers combine to form an active dimer when agonist binding occurs.
Rotation: Rotation (conformational change) of part of the receptor's transmembrane helices is caused by the ligand binding to the extracellular part of the receptor. On the intracellular side of the membrane, the rotation changes which parts of the receptor are exposed, altering how the receptor may communicate with other proteins inside the cell.