IGF-1 LR3

IGF-1 LR3 (Long R3 IGF-1) is an engineered, longer-acting version of insulin-like growth factor 1. Two modifications — an N-terminal extension and a single amino-acid swap — weaken its binding to IGF-binding proteins, so it stays active far longer than natural IGF-1. It is supplied as an analytical-grade reference material for laboratory research use only.

Natural IGF-1 is mostly held in check by IGF-binding proteins that act as brakes and reservoirs. The LR3 modifications make the protein bind those proteins much more weakly, so it escapes their control and stays free to signal — which is why it is a steady, convenient growth stimulus in the lab.

Chiefly as a cell-culture reagent and a probe of IGF-1 biology — studying how cells grow, divide, and respond to growth signals. Animal studies have also used it to examine protein metabolism, growth markers, and organ growth.

No. The published evidence is overwhelmingly preclinical — animal, cell-culture, and protein-engineering studies — with no human trials of the modified protein. It is best understood as a laboratory tool rather than a studied therapy in people.

No. It is sold strictly as a reference material for laboratory research use only — not for human or veterinary use, and not as a drug or supplement.