Half of the hormone in blood travels bound to a fragment of its own receptor

Published 26 October 2026 · REVIVE LAB UAE Research Desk · 5 min read
Leung and colleagues reported in Nature in 1987 the purification and cloning of the growth hormone receptor and showed that the high-affinity binding protein in serum was its extracellular domain, released from the cell surface by proteolytic shedding. Roughly half of growth hormone in the circulation is bound to it. The complex prolongs the hormone half-life, dampens pulses, and competes with cell-surface receptors for the hormone. Its concentration reflects receptor expression, mainly in the liver.

The 1987 finding

The receptor was purified from rabbit liver, sequenced, and its complementary DNA cloned from rabbit and human. The serum binding protein, known since the 1960s, matched the extracellular domain exactly. In humans it is generated by a metalloprotease cutting the receptor near the membrane; in rodents by alternative splicing. The same paper placed the receptor in what became the class I cytokine receptor family.

This was the first member of that family to be cloned.

What the binding protein does

Bound hormone is cleared more slowly and cannot bind cell-surface receptors, so the binding protein acts as a buffer: it smooths the pulsatile signal and holds a reserve. Its level is low in Laron syndrome, where the receptor is absent or truncated, and is used as a marker of receptor status. It also complicates measurement, since immunoassays differ in whether they see bound hormone.

The crystal structure of hormone bound to this domain is the 1992 structure described elsewhere.

Why it is on this page

The recombinant hormone in the pack is the ligand this protein binds, and the binding protein is part of the established pharmacology of the hormone in circulation. It is physiology, stated as such.

Somatropin 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
HGH Somatropin Pack24 mg (72 IU)AED 850In 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

The 1987 finding?

The receptor was purified from rabbit liver, sequenced, and its complementary DNA cloned from rabbit and human. The serum binding protein, known since the 1960s, matched the extracellular domain exactly. In humans it is generated by a metalloprotease cutting the receptor near the membrane; in rodents by alternative splicing. The same paper placed the receptor in what became the class I cytokine receptor family.

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.

HGH Somatropin Pack — in stock, dispatched from Dubai
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Related reading

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