Summary
IGF-1 LR3 (Long Arg3 Insulin-like Growth Factor-1) is an 83-amino-acid analog of human IGF-1 with two modifications: an N-terminal 13-amino-acid extension from methionyl porcine growth hormone and a single Arg-for-Glu substitution at position 3. These modifications reduce binding to IGF-binding proteins, extending functional availability.
Overview
IGF-1 LR3 is one of the most commonly used reference forms of IGF-1 in cell-culture and biochemical research. The reduced IGF-BP affinity means that more of the administered material remains available for receptor binding compared with native IGF-1, which makes it a more reproducible reagent for in-vitro studies.
Research Background
IGF-1 LR3 was developed by Tomas, Knowles, and colleagues at GroPep in Australia in the early 1990s as an IGF-1 analog with reduced IGF-binding-protein affinity. The compound has since become a widely used reference reagent in cell-culture media and in biochemical studies of IGF-1-receptor signaling.
Mechanisms Studied
Mechanistic interest centers on its agonist activity at the IGF-1 receptor, the reduced IGF-binding-protein affinity that distinguishes it from native IGF-1, and downstream signaling through the PI3K/Akt and MAPK pathways that follow receptor activation.
Published Research Summary
Tomas et al. (1993) describe the original characterization of IGF-1 LR3 and its enhanced bioactivity relative to native IGF-1. Francis et al. (1992) report on the structure-activity relationships of N-terminal IGF-1 analogs. A substantial cell-culture literature uses IGF-1 LR3 as a standard reagent for IGF-receptor signaling studies.
Quality & Verification
For research compounds, lot-level documentation is the starting point for any analytical work. Researchers commonly examine batch-specific Certificates of Analysis, reversed-phase HPLC purity readouts, mass-spectrometry confirmation of molecular weight, and lot identification to evaluate compound identity, purity, and consistency before downstream experiments.
References & Published Research
- Tomas FM et al. — Enhanced metabolic and growth-promoting effects of LR3 IGF-I in growing rats
- Francis GL et al. — Insulin-like growth factor (IGF)-I and IGF-binding proteins in plasma after administration of LR3 IGF-I
- Clemmons DR — Insulin-like growth factor-I and its binding proteins (review of IGF-BP interactions)