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Seventy residues, 7,649 daltons, and a family resemblance to proinsulin

Published 24 October 2026 · REVIVE LAB UAE Research Desk · 5 min read
Rinderknecht and Humbel reported the complete 70-residue sequence of IGF-1 in the Journal of Biological Chemistry in 1978, purified from human serum. The sequence showed about fifty per cent identity with proinsulin, organised as B, C, A and D domains: the B and A domains correspond to the two insulin chains, the C domain to the connecting peptide that insulin loses on maturation and IGF-1 keeps, and a short D extension at the carboxyl terminus. The molecular mass is 7,649 daltons. The name insulin-like growth factor followed from this result.

What was sequenced

The factor had been known as sulfation factor and then somatomedin C, defined by activity. Purifying enough from serum to sequence took years. The 1978 paper gave the structure that let the protein be made recombinantly and its receptor identified.

IGF-2, 67 residues, was sequenced by the same group the same year.

The domain organisation

B domain, residues 1 to 29; C domain, 30 to 41; A domain, 42 to 62; D domain, 63 to 70. The arrangement is proinsulin with the C peptide retained as a short loop and a D tail added. Three disulfides hold the fold, two of them in the same positions as in insulin.

The retained C domain is one reason IGF-1 binds its own receptor far better than the insulin receptor.

Why it matters for LR3

IGF-1 LR3 is this 70-residue sequence with glutamate 3 changed to arginine and 13 residues added in front. Every structural statement about IGF-1 — the domains, the disulfides, the receptor-binding surface — applies to the LR3 core.

IGF-1 LR3 is supplied by REVIVE LAB UAE for laboratory research use only, with identity and purity documented for the batch. It is not for human or veterinary use, and no dosing, administration or protocol guidance is provided.

What it costs

FormatStrengthPriceAvailability
IGF-1 LR3 Pack1 mgAED 650In stock

Delivery is AED 40 flat and free on orders over AED 700. Payment is cash on delivery anywhere in the UAE, or USDT (TRC20) in advance, which takes 5% off the order total.

Frequently asked

What was sequenced?

The factor had been known as sulfation factor and then somatomedin C, defined by activity. Purifying enough from serum to sequence took years. The 1978 paper gave the structure that let the protein be made recombinantly and its receptor identified.

Does REVIVE LAB UAE provide dosing guidance?

No. REVIVE LAB UAE supplies research materials and provides no dosing, administration or protocol guidance of any kind. Every product is sold for laboratory research use only and is not for human or veterinary consumption.

How fast is delivery in the UAE?

Stock is held in Dubai. An order confirmed before 4 PM Dubai time is dispatched the same working day, reaching Dubai and Abu Dhabi the same day and the remaining emirates within 24 hours. Delivery is AED 40 flat and free over AED 700.

IGF-1 LR3 Pack — in stock, dispatched from Dubai
HPLC-verified, lot certificate on every carton, 24-hour delivery nationwide. Browse the catalogue → All peptides UAE

Related reading

→ IGF-1 LR3 Pack — 1 mg → Three disulfides and the swap isomer → IGF-1 and the insulin receptor

Supplied for laboratory research use only. Not for human or veterinary consumption. REVIVE LAB UAE provides no dosing, administration or protocol guidance.