IGF-1 LR3: Long-Acting IGF Analog Research

IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is an 83-amino-acid analog of human IGF-1 with a molecular weight of approximately 9,111 Da. It is a long-standing reference reagent in cell-culture and preclinical research, valued for its altered binding-protein affinity. Research-grade preparations target ≥99% purity by RP-HPLC with identity confirmed by mass spectrometry.

Structure and Modifications

IGF-1 LR3 differs from native IGF-1 by two changes: an arginine substitution for glutamic acid at position 3 (the "R3" designation) and a 13-amino-acid N-terminal extension (the "Long" designation). Together these modifications substantially reduce binding to IGF-binding proteins (IGFBPs), which is the defining laboratory property of the analog.

Why the Modifications Matter

By lowering IGFBP affinity, IGF-1 LR3 exhibits a longer functional half-life in research systems than native IGF-1, making it a convenient tool compound for cell-culture experiments where sustained receptor availability is desirable. It is commonly used as a supplement in defined media research protocols studying cellular growth signaling in vitro.

Research Applications

IGF-1 LR3 is used as a reference reagent in laboratory studies of IGF-receptor signaling and cell-culture growth dynamics. It is supplied strictly for in-vitro laboratory research by qualified persons and is not for human or veterinary use.

Handling and Documentation

Supplied lyophilized, IGF-1 LR3 is reconstituted for research use and stored frozen with minimal freeze-thaw cycling to preserve integrity. Every batch ships under a numbered certificate of analysis showing RP-HPLC purity and mass-spectrometry identity, retrievable from the batch verification tool.