IGF-1 LR3 is a modified analog of insulin-like growth factor 1 carrying an arginine substitution and a 13-amino acid N-terminal extension, changes that curb its binding to IGF binding proteins and extend its circulating half-life well beyond that of native IGF-1.
It acts on the IGF-1 receptor to trigger PI3K/Akt and MAPK/ERK signaling, and studies of local IGF-1 overexpression in mouse muscle found increased muscle mass through both fiber hypertrophy and satellite cell driven hyperplasia.
This has made it a tool in research on cell proliferation and skeletal muscle growth signaling.
