Insulin-like Peptide 3 (INSL3)

Also known as INSL3; relaxin-like factor; RLF

An insulin-superfamily ligand for RXFP2, studied in receptor assays and models of gubernacular development.

Length: 57 amino acids across two chains in the commonly studied mature human form
Half-life: Not well characterised
Mechanism: INSL3 binds and activates relaxin family peptide receptor 2 (RXFP2), commonly producing Gs-dependent cAMP accumulation. Its B chain contributes strongly to receptor binding, while the intact peptide structure supports receptor activation.
Studied in: RXFP2-expressing cells, gubernacular tissue preparations and genetically modified animal models are used to study receptor pharmacology and reproductive development.

About Insulin-like Peptide 3 (INSL3)

INSL3 was identified through studies of Leydig cell gene expression and was initially described as a relaxin-like factor. The human precursor contains a signal peptide, B-chain region, connecting segment and A-chain region. The commonly studied mature construct comprises a 31-residue B chain and a 26-residue A chain, joined through the insulin-superfamily disulphide pattern. Leydig cells are a major source, although expression also occurs in ovarian theca cells.

RXFP2, previously designated LGR8, is the established receptor target for INSL3. Genetic disruption of either ligand or receptor in mice demonstrates the importance of this signalling axis in gubernacular development and testicular descent. In recombinant assays, cAMP accumulation is a common functional endpoint. Binding experiments and peptide truncation studies help distinguish receptor recognition from activation, while comparisons across species require attention to both ligand sequence and receptor background.

Laboratory notes

Check the supplied chain boundaries and disulphide mapping, as precursor-derived and engineered constructs are not interchangeable.
Pair RXFP2 binding measurements with functional assays to distinguish receptor affinity from signalling efficacy.
Record receptor species and expression level, and include matched receptor-negative controls when comparing constructs.

Storage and reconstitution basics: storage guide.

Questions about Insulin-like Peptide 3 (INSL3)

Is INSL3 an insulin receptor ligand?

Its classification reflects structural membership of the insulin superfamily. RXFP2, rather than the insulin receptor, is its established physiological receptor.

Why can INSL3 fragments bind without strongly activating RXFP2?

Receptor recognition and activation depend on overlapping but distinct structural features. A fragment may retain binding contacts while lacking features needed to stabilise an active receptor conformation.

Which animal models clarify INSL3 function?

Insl3- and Rxfp2-deficient mice are established models for investigating gubernacular differentiation and testicular positioning during development.

Is Insulin-like Peptide 3 (INSL3) for human use?

No. It is supplied strictly for in-vitro laboratory research and is not for human or animal consumption.

Related research peptides

All products are sold for laboratory research use only. Not for human consumption, not a medicine, not for diagnosing, treating or preventing any condition.