An 83-amino-acid analogue of insulin-like growth factor 1, modified with an arginine substitution at position 3 and a 13-residue N-terminal extension. It is commonly used in cell-culture research.

Native IGF-1 binds tightly to a family of binding proteins, which makes free concentrations hard to control in culture. Both modifications lower that affinity, giving a more predictable free fraction.

What does the LR3 name mean?

Long R3: the 'Long' refers to the N-terminal extension, and R3 to the arginine substitution at the third position.

1 mg of lyophilised powder in a sealed crimp-top vial, assayed at ≥99% purity by HPLC-UV with identity confirmed by LC-MS.

Is a certificate of analysis available?

Yes. A batch-level certificate is issued against the lot number and covers the material you receive.

IGF-1 LR3

Modified IGF-1 analogue studied for reduced binding-protein affinity

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Every batch verified by an independent lab, not by us
Tested in America. Ships within 1 business day, stored frozen, stable at room temperature until you mix it
Retest it at any lab. If it doesn't match our report, every dollar back

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IGF-1 receptorreceptor binding

Binding-protein evasionfree fraction

Downstream signallingcell models

How IGF-1 LR3 works

Researchers study IGF-1 LR3 as acting through three broad routes.

IGF-1 receptorreceptor binding

It is studied as a ligand at the IGF-1 receptor, the same target as the native growth factor.

Binding-protein evasionfree fraction

The substitutions are studied for lowering affinity to IGF binding proteins, raising the free fraction in culture.

Downstream signallingcell models

Cell work examines the PI3K/Akt and MAPK cascades downstream of receptor engagement.

For research use only. Mechanisms described reflect published preclinical literature.

What the studies found

Published findings on this compound, each linked to its source. Animal and lab results are context, not claims about this product.

PotencyPreclinical

6×

In growing rats over 14 days, LR3 IGF-1 matched native IGF-1's 18 to 26% gains in body weight, protein retention and feed efficiency at about one-sixth the dose.

vs native IGF-1

J Endocrinol 1993 · rat study

Native IGF-1full dose

LR3 IGF-1≈1/6 dose

Dose needed for the same gains over 14 days

Gut growthPreclinical

+47%

In normal rats given LR3 IGF-1 for 14 days, small-intestine weight rose 47% and total gut weight 43%, with deeper crypts and taller villi lining the gut.

vs untreated rats

Small intestine weight+47%

Total gut weight+43%

Small intestine length+13%

Change after 14 days at the highest dose

Am J Physiol 1994 · rat study, n=6/group

Diabetic ratsPreclinical

2.5–3×

In diabetic rats, LR3 IGF-1 restored growth 2.5 to 3 times more potently than native IGF-1, and the IGF peptides raised muscle protein-building rates by up to 50%.

vs native IGF-1

Native IGF-11×

LR3 IGF-12.5–3×

Relative potency in restoring growth

Biochem J 1993 · rat study