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I learnt about carrier proteins; how they bind a substrate/molecule, undergo a conformational change, and release the substrate/molecule on the other side of the membrane. We can take Glucose transporters(GLUTs) as an example.

I see this "binding" to the carrier protein as something similar to how ligands interact with receptors. However, I don't know whether it is correct to classify carrier proteins as receptors.

Please help.

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  • $\begingroup$ PS: Carrier proteins don't seem to fall into any of the types of receptors -- ionotropic, G-protein-coupled, or enzyme-linked. $\endgroup$
    – Chemo-Mike
    Jul 3, 2022 at 15:13
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    $\begingroup$ Welcome to SE Biology. Please finish the Tour and the Help on asking questions to find out how this site operates. Specifically we expect posters to show that they have researched the question to try to find the answer themselves. If you search for "Receptor" in Wikipedia, taking the Biochemistry variety you will find how the term is used in biological science (rather than general English). Specifically it relates to signal transduction, answering your question in the negative. $\endgroup$
    – David
    Jul 3, 2022 at 22:53

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They are different molecules.

From Cell and Molecular Biology, Concepts and Experiments, 7th Ed., Karp"

Cells can only respond to a particular extracellular message if they express receptors that specifically recognize and bind that messenger molecule. The molecule that binds to the receptor is called a ligand. Different types of cells possess different complements of receptors, which allow them to respond to different extracellular messengers.

From Molecular Biology of the Cell, 5th Ed., Alberts:

Transporters (also called carriers, or permeases) bind the specific solute to be transported and undergo a series of conformational changes to transfer the bound solute across the membrane.

If one generalizes the definition, transporters may elicit signaling via indirect mechanisms, but the two classes are still distinct:

In contrast to bona fidae receptors, transporters and channels mediate the uptake of solutes, metabolites, drugs or ions, which themselves can act as molecular signals, once intracellularly accumulated.

The newly-identified transceptors possess both properties at the same time:

A relative newcomer in environment sensing are the so called transceptors, membrane proteins that possess both solute transport and receptor-like signaling activities.

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