biology

GPR173

GPR173 is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand GPR173 rather than just read about it. In short: Probable G-protein coupled receptor 173 is a protein that in humans is encoded by the GPR173 gene. Function GPR173 (Also known as Super-Conserved Receptor Expressed in Brain 3, or SREB3) is a highly conserved G protein-coupled receptor (GPCR) that plays a significant role in the regulation of the hypothalamic-pituitary-gonadal (HPG) axis, which is central to reproductive function.

Key takeaways

GPR173 belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect GPR173 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of GPR173 from memory before moving on to harder problems.

Reference excerpt

Probable G-protein coupled receptor 173 is a protein that in humans is encoded by the GPR173 gene.

Function GPR173 (Also known as Super-Conserved Receptor Expressed in Brain 3, or SREB3) is a highly conserved G protein-coupled receptor (GPCR) that plays a significant role in the regulation of the hypothalamic-pituitary-gonadal (HPG) axis, which is central to reproductive function. It is expressed in the brain and ovaries, where it is considered the putative receptor for the peptide hormone phoenixin (PNX). Activation of GPR173 by phoenixin potentiates the secretion of luteinizing hormone (LH) in response to gonadotropin-releasing hormone (GnRH), thereby promoting ovarian cycling and supporting reproductive processes. Beyond reproduction, GPR173 has been implicated in diverse physiological functions such as food intake regulation, learning and memory, anxiety, inflammatory responses, and cardiac protection, largely through its modulation by phoenixin. Additionally, GPR173 may act as a receptor for cholecystokinin (CCK) in certain brain regions, mediating inhibitory synaptic plasticity and potentially serving as a therapeutic target for disorders involving excitation-inhibition imbalance. The expression of GPR173 can be influenced by nutritional and environmental factors, indicating its role as a sensor and mediator in integrating external signals with neuroendocrine pathways.

Ligands GPR173 is an orphan class GPCR, however recent work has identified several compounds that may function as endogenous ligands.

Phoenixin Recent studies have found GPR173 may act as a receptor for the peptides phoenixin-14 (PNX-14) and phoenixin-20 (PNX-20). Both Phoenixins are alternate cleavage products of SMIM20. PNX-20 treatments increased CREB phosphylation (pCREB) and ERK1/2 phosphorylation (pERK1/2) in various cell lines. These effects of PNX-20 were found to be dependent on GPR173 expression. PNX-14 treatments were found to increase intracellular cAMP treatments under specific conditions within adipocytes. As a ligand for GPR173, PNX-20 was found to have self regulatory behaviors by increasing GPR173 expression.

GnRH-(1-5) GnRH-(1-5) is a degradation product of GnRH. GnRH-(1-5) was found to induce STAT3 phosphorylation (pSTAT3) in GN11 cells. GnRH-(1-5) was not found to affect cAMP levels or IP1 levels in GN11 cells, and did not recruit Gα12 or Gα13 to GPR173. Activation of a G subunit associated pathway could not be confirmed, however GnRH-(1-5) treatments did have GPR173 recruit β-Arrestin 2 and PTEN. GnRH-(1-5) induced production of pSTAT3 via GPR173 was found to be dependent on PTEN activity.

Cholecystokinin 8 (CCK8) CCK8 has been found to interact with GPR173 in cell surface binding assays utilizing Flag-Tag assays. CCK1R and CCK2R are established receptors for CCk8 that signal through Gαq/11. In GPR173+/+ CHO cells, CCK8 was found to mobilize [Ca2+]i with similar EC50 compared to CCK1R and CCK2R.

Illustrations

Worked examples

Example 1 — a first encounter with GPR173

Start with the simplest possible case. Write down what GPR173 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to GPR173 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about GPR173 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of GPR173

In research: GPR173 appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses GPR173 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: GPR173 is common in secondary-school and first-year university syllabi. It links to neighbouring topics G protein-coupled receptors, Genes on human chromosome X, so understanding it makes those chapters shorter.
In everyday life: Look for GPR173 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study GPR173 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what GPR173 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain GPR173 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is GPR173 in simple terms?

Probable G-protein coupled receptor 173 is a protein that in humans is encoded by the GPR173 gene. Function GPR173 (Also known as Super-Conserved Receptor Expressed in Brain 3, or SREB3) is a highly conserved G protein-coupled receptor (GPCR) that plays a significant role in the regulation of the h…

Why does GPR173 matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study GPR173?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on GPR173.