HCG

Human chorionic gonadotropin (hCG) is a heterodimeric glycoprotein hormone composed of a common α-subunit shared with LH, FSH, and TSH, and a hormone-specific β-subunit that confers receptor identity. Extensive glycosylation stabilizes the assembled dimer and prolongs its circulating half-life relative to luteinizing hormone. It is a naturally occurring gonadotropin studied here as a reference endocrine glycoprotein. Because it is a folded, glycosylated protein rather than a short synthetic peptide, it is handled with the care appropriate to a labile macromolecule.

The research literature characterizes hCG as an agonist at the luteinizing-hormone/choriogonadotropin receptor (LHCGR), the same class-A G-protein-coupled receptor engaged by luteinizing hormone. Receptor binding is coupled to Gs-protein and adenylate-cyclase activation, raising intracellular cyclic-AMP and activating protein-kinase-A signaling. In gonadal-cell models this cascade drives steroidogenic gene expression and steroid output — testosterone synthesis in Leydig cells and progesterone and estrogen precursors in ovarian thecal and granulosa cells. Its activity is characterized at the receptor and gonadal-cell level within the hypothalamic-pituitary-gonadal axis.

Contexts in which this compound appears in the in-vitro and preclinical research literature:

• Leydig-cell culture: LHCGR-coupled cAMP/PKA signaling and steroidogenic-enzyme expression.
• Ovarian thecal and granulosa-cell models of follicular steroidogenesis.
• Comparative receptor pharmacology against luteinizing hormone (binding kinetics, half-life).
• Preclinical studies of gonadotropin signaling within the hypothalamic-pituitary-gonadal axis.
• Glycosylation studies examining subunit assembly and receptor-binding stability.

Supplied as a lyophilized preparation standardized in international units (IU) rather than by mass. Reconstitute gently with bacteriostatic water to the working activity your protocol requires (e.g. adding 1 mL to a 10,000 IU vial yields 10,000 IU/mL). Direct the diluent down the vial wall and swirl slowly; do not shake or vortex, as mechanical agitation can denature the glycoprotein. Aliquot after reconstitution to avoid repeated freeze–thaw.

Store the sealed lyophilized vial at −20 °C protected from light. Once reconstituted, the glycoprotein is comparatively labile — keep refrigerated at 2–8 °C, use within a short assay window, and avoid repeated freeze–thaw.

Independent and in-house certificates published for this compound. Each reports identity and HPLC purity for the tested lot.