HGH 191aa (Somatropin): A Research Reference Guide
By Lemon Labs Research Desk · Updated July 8, 2026
In short
HGH 191aa is recombinant human growth hormone (somatropin) — a 191-amino-acid single-chain protein identical in sequence to endogenous human growth hormone. In research it is studied for its action on the growth-hormone receptor and the downstream IGF-1 axis. It is a research-use-only reference protein.
What is HGH 191aa?
HGH 191aa is recombinant human growth hormone, a 191-amino-acid polypeptide whose sequence matches naturally occurring human growth hormone. The "191aa" designation specifies the full-length, correctly-sequenced protein, which researchers use as a reference standard for growth-hormone studies.
The GH / IGF-1 axis in research
Growth hormone acts on the growth-hormone receptor and stimulates production of insulin-like growth factor 1 (IGF-1), largely in the liver. Researchers study this GH→IGF-1 cascade in cell and animal models. Compounds like CJC-1295, ipamorelin, and tesamorelin act *upstream* to influence GH release; HGH 191aa is the hormone itself.
Handling and quality
Recombinant protein is supplied lyophilized and is sensitive to heat and agitation; store cold, sealed, and protected from light, and reconstitute gently in the lab. Confirm identity and ≥99% purity on the lot Certificate of Analysis.
Research-use-only statement
This compound is supplied strictly for in-vitro research and laboratory use. It is not a drug, supplement, food, or cosmetic, has not been evaluated by the FDA, and is not intended to diagnose, treat, cure, or prevent any disease. It is not for human or veterinary use. All information here summarizes published scientific literature for educational purposes for qualified researchers — it is not medical advice and does not describe human administration.
Reference compounds mentioned
Frequently asked
What does "191aa" mean?
It denotes the full-length 191-amino-acid form of recombinant human growth hormone, matching the natural human sequence — the correctly-sequenced reference form used in research.
How does HGH differ from GH secretagogues like ipamorelin?
HGH 191aa is growth hormone itself; secretagogues (ipamorelin) and GHRH analogs (CJC-1295, tesamorelin) act upstream to influence the body’s own GH release in research models.
Is HGH 191aa for human use?
No. It is a research-use-only reference protein, not for human or veterinary use.