HCG (Human Chorionic Gonadotropin) — wholesale 10-vial kits

Research context

Human chorionic gonadotropin belongs to the glycoprotein hormone family with LH, FSH and TSH. All four share the same α subunit; the β subunit gives each hormone its receptor specificity. hCG's β subunit is the longest of the family, carrying a C-terminal extension of roughly 30 residues with several O-linked glycosylation sites that the LH β subunit lacks. Together with N-linked glycans on both subunits, carbohydrate makes up roughly a third of the molecule's mass, which is why hCG's mass is quoted as an approximate glycoprotein value rather than a single exact figure.

The 1994 crystal structure from Lapthorn and colleagues (Nature) showed that both subunits adopt a cystine-knot fold, and that a segment of the β subunit wraps around the α subunit like a seat belt, which explains the stability of the heterodimer. That structure is the reference point for most structure–function work on the glycoprotein hormones and their receptors.

hCG acts at the LH/CG receptor (LHCGR), a class A G-protein-coupled receptor with a large leucine-rich extracellular domain that binds the hormone. LHCGR couples mainly to Gs and cAMP, with Gq / phospholipase C signaling at higher receptor occupancy, as reviewed by Ascoli and colleagues in Endocrine Reviews (2002). Because hCG and LH share the receptor but differ in their β subunits and glycosylation, hCG is a standard tool for comparing ligand-specific signaling at one receptor.

Typical laboratory uses include LHCGR binding and cAMP-accumulation assays in recombinant cell lines; steroidogenesis assays in Leydig-cell and granulosa-cell models, where cAMP-driven testosterone or progesterone output is the readout; studies of hCG isoforms, including hyperglycosylated hCG and the free β subunit, which Cole (2010) reviews as distinct molecules with distinct biology; and use as a calibrator or control antigen when developing and validating hCG immunoassays.

Potency is expressed in International Units (IU) rather than milligrams because the specific activity of a glycoprotein depends on its glycosylation. IU are defined against a World Health Organization international standard, so a laboratory comparing lots or suppliers should compare IU per vial and check that the stated activity is traceable to that standard. This item is supplied as 5,000 IU of lyophilized hCG per vial.

Regulatory position, stated factually: hCG is the active ingredient of FDA-approved drug products such as Novarel and Pregnyl. The material sold here is a research reagent, not a drug product, and is supplied for in-vitro and preclinical laboratory research only. Identity on each lot COA is confirmed against the hCG heterodimer, with activity reported in IU.

Research areas

• LH/CG receptor (LHCGR) binding and cAMP signaling
• Leydig-cell and granulosa-cell steroidogenesis assays
• glycoprotein hormone structure and glycosylation
• hCG isoforms, hyperglycosylated hCG and free β subunit
• immunoassay calibrator and control antigen
• comparative LH vs hCG signaling at one receptor

U.S. regulatory status of the compound (as an active ingredient): FDA-approved active ingredient (Novarel, Pregnyl). Supplied here as a research reagent, not the drug product. The material sold here is a research reference chemical, not a drug product.

Handling and storage

• Store lyophilized vials refrigerated or frozen as stated on the label, sealed and protected from light.
• Let the vial reach room temperature before opening to limit condensation.
• Reconstitute in an appropriate sterile buffer following your laboratory SOP; glycoproteins can adsorb to plastics, so low-binding tubes are common practice.
• Aliquot reconstituted material and avoid repeated freeze–thaw, which reduces biological activity.