Insulin–relaxin-family neuropeptide
Relaxin-3
Relaxin-3, also called INSL7, is a neuropeptide in the insulin–relaxin family. Its name does not make it insulin or relaxin-2. Discovery studies combined molecular isolation, receptor recognition and anatomical distribution.
This is a research reference, not a product offered in the Asciende catalog. Published studies do not establish the identity, purity or availability of a commercial preparation.
Receptor, selectivity and context
Record the receptor panel actually measured. Absence of a result for another receptor does not establish absence of activity.
- Which receptor subtype and species were evaluated?
- Was affinity, functional potency or an integrated response measured?
- Does the comparison include the alternative receptors needed for a selectivity claim?
Mechanism described in the literature
In cells overexpressing GPCR135, now called RXFP3, recombinant human relaxin-3 stimulated G-protein activation indicators and reduced cyclic AMP accumulation in vitro. Recognition was also examined with a labeled ligand, providing complementary evidence.
Other names in the literature
- Relaxin-3
- H3 relaxin
- INSL7
From brain extract to an identified ligand
The 2003 investigation began with activity in animal-brain extracts and isolated the ligand from pig brain. It then connected the product to the relaxin-3 gene and examined recombinant material. Distinguishing an extract, an isolated molecule and a recombinant preparation shows which evidence established identity and which characterized function.
Localization supported a circuit hypothesis
The work combined cellular pharmacology with transcript maps in brain regions. Distribution supported a proposed relationship between brainstem structures and the hypothalamus in the animals studied. An anatomical map alone, however, does not establish a particular behavior or the response of every neuron in a region.
Experimental activity was not confined to one receptor
An accompanying study showed functional recognition of relaxin-3 by GPCR142 in vitro and examined its distribution across tissues and species. Its relationship to RXFP3 should therefore not be described as absolute exclusivity. Selecting a receptor to investigate a circuit requires anatomical and functional context as well as activity in receptor-expressing cells.
Questions and answers
Does INSL7 mean relaxin-3 is insulin?
No. It is a historical name for a distinct entity within a related molecular family.
Does receptor binding demonstrate a brain function?
Not by itself. Binding must be connected to expression, localization and appropriate functional experiments.
Sources
- Identification of relaxin-3/INSL7 as an endogenous ligand for the orphan G-protein-coupled receptor GPCR135. — J Biol Chem, 2003
- Identification of relaxin-3/INSL7 as an endogenous ligand for the orphan G-protein-coupled receptor GPCR135.
- Identification of relaxin-3/INSL7 as a ligand for GPCR142. — J Biol Chem, 2003
- Identification of relaxin-3/INSL7 as a ligand for GPCR142.