The Growth Hormone Secretagogue Receptor Family: From Orphan Receptor to Ghrelin Discovery
Characterization of the GHS-R family revealed a constitutively active receptor with ghrelin as its natural ligand and a related receptor (GHS-R1b) whose function remains unknown, mapping the complete receptor system.
Quick Facts
What This Study Found
The GHS-R family includes the active GHS-R1a (ghrelin receptor, constitutively active) and the orphan GHS-R1b splice variant, with constitutive activity suggesting baseline signaling roles and inverse agonist therapeutic potential.
Key Numbers
How They Did This
In-vitro receptor characterization using cloned GHS-R1a and GHS-R1b. Binding, signaling, and constitutive activity assessed in expression systems.
Why This Research Matters
Constitutive activity means the ghrelin receptor signals even when ghrelin isn't present. This has implications for appetite regulation (baseline hunger signaling) and drug development (inverse agonists could reduce this baseline signal for appetite suppression).
The Bigger Picture
Constitutively active receptors change the therapeutic landscape — you can not only activate them (agonists) or block them (antagonists) but also suppress their baseline activity (inverse agonists). For the hunger receptor, this could mean true appetite suppression.
What This Study Doesn't Tell Us
In-vitro characterization. GHS-R1b's function remains undetermined. Constitutive activity in expression systems may differ from native tissue.
Questions This Raises
- ?Do inverse agonists at GHS-R1a suppress appetite?
- ?What is GHS-R1b's function?
- ?Does constitutive GHS-R1a activity contribute to baseline hunger?
Trust & Context
- Key Stat:
- Always on The ghrelin receptor signals even without ghrelin — this constitutive activity may drive baseline hunger and represents a unique drug target
- Evidence Grade:
- Preliminary receptor characterization from the group that cloned GHS-R, providing authoritative data on the complete receptor family.
- Study Age:
- Published in 2001. GHS-R1a constitutive activity has been confirmed and is now targeted by inverse agonist drug candidates for obesity.
- Original Title:
- Growth hormone secretagogue receptor family members and ligands.
- Published In:
- Endocrine, 14(1), 9-14 (2001)
- Authors:
- Smith, R G(15), Leonard, R(2), Bailey, A R(6), Palyha, O, Feighner, S, Tan, C, Mckee, K K, Pong, S S, Griffin, P, Howard, A
- Database ID:
- RPEP-00699
Evidence Hierarchy
Frequently Asked Questions
What does a constitutively active receptor mean?
Most receptors sit quietly until a hormone activates them. The ghrelin receptor is different — it's always partially active, sending a constant low-level hunger signal. This may explain baseline appetite drive.
Could this help treat obesity?
Yes. Inverse agonists — drugs that suppress the receptor's baseline activity — could reduce the constant hunger signal. This is a fundamentally different approach from simply blocking ghrelin binding.
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Cite This Study
https://rethinkpeptides.com/research/RPEP-00699APA
Smith, R G; Leonard, R; Bailey, A R; Palyha, O; Feighner, S; Tan, C; Mckee, K K; Pong, S S; Griffin, P; Howard, A. (2001). Growth hormone secretagogue receptor family members and ligands.. Endocrine, 14(1), 9-14.
MLA
Smith, R G, et al. "Growth hormone secretagogue receptor family members and ligands.." Endocrine, 2001.
RethinkPeptides
RethinkPeptides Research Database. "Growth hormone secretagogue receptor family members and liga..." RPEP-00699. Retrieved from https://rethinkpeptides.com/research/smith-2001-growth-hormone-secretagogue-receptor
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkPeptides research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.