Growth hormone receptor (GHR) is a single-pass transmembrane cytokine receptor — not a tyrosine kinase receptor — that signals through associated JAK2 kinase and downstream STAT5 transcription factors. GHR engagement on tendon fibroblasts is the documented mechanistic finding in the canonical BPC-157 tendon-healing study.
Definition
Growth hormone receptor is a Class I cytokine receptor expressed across most tissues, with high expression in liver, muscle, bone, and tendon. The receptor binds growth hormone (somatotropin) as a single ligand molecule that bridges two receptor subunits and induces a functional dimer rearrangement. Unlike tyrosine kinase receptors which carry intrinsic intracellular kinase domains, GHR has no catalytic activity of its own. Signal transduction depends on the constitutively associated JAK2 kinase, which trans-autophosphorylates upon receptor dimerisation and then phosphorylates tyrosine residues on the receptor’s intracellular tail. These phosphotyrosines serve as docking sites for STAT5 transcription factors, which are themselves phosphorylated by JAK2, dimerise, and translocate to the nucleus to drive gene-expression responses.
Downstream of the canonical JAK2-STAT5 axis, GHR engagement also activates MAPK, PI3K-Akt, and SHC-Grb2-Ras cascades. A major downstream output is hepatic synthesis and release of insulin-like growth factor 1 (IGF-1), which mediates many of the tissue-level anabolic effects historically attributed to growth hormone itself.
How growth hormone receptor is studied in peptide research
GHR expression is measured by Western blot, quantitative PCR for receptor transcript, and surface receptor density by flow cytometry on cells expressing the receptor. Activation is assayed by phospho-JAK2 and phospho-STAT5 Western blot. Pharmacological GH-receptor antagonism (pegvisomant for human studies; small-molecule inhibitors in preclinical work) and genetic loss-of-function in JAK2 or STAT5 are used to confirm cascade involvement.
For BPC-157, the canonical tendon-fibroblast study by Chang and colleagues documented growth-hormone-receptor up-regulation alongside the promoting effects on tendon-explant outgrowth, cell survival, and migration (PMID 21030672). The musculoskeletal-soft-tissue-healing review consolidates the receptor-engagement findings across the wider tendon and ligament literature (PMID 30915550). Growth hormone secretagogues and GHRH analogues are a separate compound class that act upstream of GHR by stimulating endogenous GH release from the pituitary; ipamorelin (PMID 9849822) and CJC-1295 (PMID 19386527) are research compounds in this class with documented effects on the GH/IGF-1 axis at the receptor-level downstream.
Related terms
- BPC-157
- Tendon fibroblast
- Tyrosine kinase receptor (GHR is NOT in this class)
- JAK2 / STAT5 signalling
- IGF-1 / insulin-like growth factor 1
- GH (growth hormone, somatotropin)
- GHRH receptor
Compounds where growth hormone receptor appears in the mechanism literature
- BPC-157 — GHR up-regulation documented in tendon fibroblast culture; mechanistic finding in the canonical Chang tendon-healing study
- Ipamorelin — growth hormone secretagogue that acts upstream of GHR by stimulating endogenous GH release
- CJC-1295 No DAC — long-acting GHRH analogue that acts upstream of GHR via increased GH pulse amplitude
- Tesamorelin — synthetic GHRH analogue acting upstream of GHR via the GHRH-receptor on pituitary somatotrophs
References
- Chang CH et al. The promoting effect of pentadecapeptide BPC 157 on tendon healing involves tendon outgrowth, cell survival, and cell migration. J Appl Physiol 2011;110(3):774-780. [PMID 21030672]
- Cerovecki T et al. Gastric pentadecapeptide body protection compound BPC 157 and musculoskeletal soft tissue healing. Cell Tissue Res 2019. [PMID 30915550]
- Raun K et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol 1998;139(5):552-561. [PMID 9849822]
- Sackmann-Sala L et al. Activation of the GH/IGF-1 axis by CJC-1295, a long-acting GHRH analog, results in serum protein profile changes in normal adult subjects. Growth Horm IGF Res 2009. [PMID 19386527]
Glossary entries describe research-context use of peptide-research terminology. They do not constitute medical, veterinary, or clinical advice. Every compound in the Ronin catalog is sold strictly for laboratory and research use only.