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Compound guide
HCG: what the research covers
A two-subunit glycoprotein that binds the luteinising hormone receptor and stays in circulation for hours rather than minutes. The sugars, not the protein, are what buy it that time.
What HCG is
Human chorionic gonadotropin is a non-covalent heterodimer. The alpha subunit, ninety-two residues, is shared with LH, FSH and TSH; the beta subunit is specific to HCG and carries a twenty-four residue carboxy-terminal extension that none of the others have. Both subunits are N-glycosylated and the beta extension carries O-linked sugars as well.
That carbohydrate is the functional story. The polypeptide determines which receptor is engaged; the glycans determine how long the molecule survives in circulation, and HCG survives far longer than LH despite acting at the same receptor, LHCGR, through Gs, adenylate cyclase and protein kinase A.
The practical upshot is a long-acting LH surrogate, which is why decades of LHCGR pharmacology was done with HCG rather than with LH itself.
Three literatures, one molecule
The steroidogenesis literature is the largest: cultured Leydig and granulosa cells respond to HCG with cyclic AMP accumulation and steroid output, which is the standard functional readout for the receptor, and sustained exposure produces desensitisation that is itself well studied.
The second is placental. HCG is a trophoblast product and a trophoblast signal, and work on implantation, placental development and trophoblast differentiation uses it as both.
The third is analytical. HCG is the analyte behind pregnancy immunoassays, and because its beta subunit is unique while its alpha subunit is shared, it is the reference material against which subunit-specific antibody cross-reactivity is characterised. It is also a tumour marker in germ cell disease, which gives the assay literature a clinical dimension.
Compared with HMG, which carries both FSH and LH-like activity, HCG is the clean single-receptor agonist — which is exactly why the two are often run together.
How Amino Club supplies it
Supplied lyophilised in sealed vials as HCG, specified in international units and released against the Certificate of Analysis for its own batch; the lab testing page documents the release sequence.
Glycoprotein hormones are specified by activity rather than by mass, because glycosylation varies and activity does not track molecular weight. In handling they behave as proteins: adsorption to surfaces at low concentration, loss of activity on vigorous agitation, poor tolerance of repeated freeze-thaw cycling. Laboratories keep the sealed vial cold, prepare small working volumes and do not refreeze them. Diluents are under reconstitution supplies, and preservative-free water is usually indicated where a cell-based assay follows.
Related reading
HCG sits in the sexual health and reproductive research peptides group with HMG, gonadorelin and kisspeptin upstream of it, and PT-141 and oxytocin acting on behaviour rather than on the gonad.
Every guide is indexed in the research library. Certificates and storage are covered on the FAQ, quantity pricing through bulk and wholesale.
Research use only
HCG supplied by Amino Club is a laboratory reference material. It is not a medicine, not a supplement, and not for human or veterinary use, and no dosing guidance or administration protocol is provided. The full terms are in the research use policy.