Chorionic Gonadotropin β-subunit human

G1299 is a heterologously expressed β subunit of the heterodimeric hormone human chorionic gonadotropin (hCG) that is typically found endogenously in a complex with the α subunit.

The polypeptide chain is approximately 16.4 kDa, but is highly glycosylated which results in a heterogeneous mixture of molecules with different molecular weights ranging from approximately 16 to 64 kDa as assessed by SDS-PAGE. There are two N-linked glycosylation sites that are known to be at least partially occupied both endogenously and when expressed in Pichia pastoris.¹ P. pastoris N-glycosylate proteins with high-mannose glycoforms typically ranging from Man_8-14 GlcNac₂.² There are also four O-linked glycosylation sites on the C-terminal end, which are less well characterized, but are likely at least partially occupied when expressed in P. pastoris as treatment with the N-glycosidase PNGase F (Sigma Product #: F8435) does not entirely consolidate the migration of the protein by SDS-PAGE.

Product Number G1299 is packed in vials containing ≥ 150 μg of protein as assessed by absorption at 280 nm using the extinction coefficient 5,520 M-¹cm-¹ and MW: 16,354.8 g/mol. Oligosaccharide content from glycosylation is not considered in the final formulation for vial quantity.

The signal peptide of hCG-β has been truncated for this product and a 6 x Histidine fusion tag is in its place on the N-terminus directly adjacent to the hCG-β polypeptide. The N-terminal sequence is as follows: HHHHHHSKEPLR…

The interaction of hCG-β with antibodies is known to be highly variable. There are multiple forms of the molecule found endogenously including degraded hCG, subunit fragments, hypoglycosylated, hyperglycosylated, and nicked hCG.³ This gives rise to variability in the interaction with antibodies, of which are raised against a variety of epitopes. Due to these complications G1299 has been tested via dot blot as an antigen against anti-human hCG antibodies to qualitatively verify its performance in antibody-based assays. Due to variability between antibodies it is suggested to screen for an optimal concentration of G1299 for your specific application.

CGB5 (chorionic gonadotropin β5) rs7260002 polymorphism is linked with reduced risk of recurrent spontaneous abortion (RSA) in Chinese population. Methylation allelic polymorphism (MAP) in this gene has been found to be linked with miscarriage and pregnancy loss. This protein shows expression in ovarian carcinoma tissues, whereas its expression is absent in non-cancerous tissues.

This recombinant hCG-beta has been confirmed to interact with anti-hCG antibodies via dot blot.