CGB2 (gene) explained

Choriogonadotropin subunit beta variant 2 is a protein that in humans is encoded by the CGB2 gene.^{[1] [2]}

The beta subunit of chorionic gonadotropin (CGB) is encoded by six highly homologous and structurally similar genes that are arranged in tandem and inverted pairs on chromosome 19q13.3, and contiguous with the luteinizing hormone beta (LHB) subunit gene. The CGB genes are primarily distinguished by differences in the 5' untranscribed region. This gene was originally thought to be one of the two pseudogenes (CGB1 and CGB2) of CGB subunit, however, detection of CGB1 and CGB2 transcripts in vivo, and their presence on the polysomes, suggested that these transcripts are translated. To date, a protein product corresponding to CGB2 has not been isolated. The deduced sequence of the hypothetical protein of 132 aa does not share any similarity with that of functional CGB subunits.^[3] However, a 163 aa protein, translated from a different frame, is about the same size, and shares 98% identity with other CGB subunits.

Further reading

• Bo M, Boime I . Identification of the transcriptionally active genes of the chorionic gonadotropin beta gene cluster in vivo . The Journal of Biological Chemistry . 267 . 5 . 3179–3184 . February 1992 . 1371113 . 10.1016/S0021-9258(19)50712-8 . free .
• Policastro PF, Daniels-McQueen S, Carle G, Boime I . A map of the hCG beta-LH beta gene cluster . The Journal of Biological Chemistry . 261 . 13 . 5907–5916 . May 1986 . 2422163 . 10.1016/S0021-9258(17)38469-7 . free .
• Julier C, Weil D, Couillin P, Côté JC, Nguyen VC, Foubert C, Boué A, Thirion JP, Kaplan JC, Junien C . The beta chorionic gonadotropin-beta luteinizing gene cluster maps to human chromosome 19 . Human Genetics . 67 . 2 . 174–177 . 1984 . 6204923 . 10.1007/BF00272995 . 25631308 .
• Talmadge K, Boorstein WR, Fiddes JC . The human genome contains seven genes for the beta-subunit of chorionic gonadotropin but only one gene for the beta-subunit of luteinizing hormone . DNA . 2 . 4 . 281–289 . 1984 . 6319099 . 10.1089/dna.1983.2.281 .
• Talmadge K, Vamvakopoulos NC, Fiddes JC . Evolution of the genes for the beta subunits of human chorionic gonadotropin and luteinizing hormone . Nature . 307 . 5946 . 37–40 . 1984 . 6690982 . 10.1038/307037a0 . 4282776 . 1984Natur.307...37T .
• Dirnhofer S, Hermann M, Hittmair A, Hoermann R, Kapelari K, Berger P . Expression of the human chorionic gonadotropin-beta gene cluster in human pituitaries and alternate use of exon 1 . The Journal of Clinical Endocrinology and Metabolism . 81 . 12 . 4212–4217 . December 1996 . 8954017 . 10.1210/jcem.81.12.8954017 . free .
• Hallast P, Rull K, Laan M . The evolution and genomic landscape of CGB1 and CGB2 genes . Molecular and Cellular Endocrinology . 260-262 . 9 . 2–11 . January 2007 . 17055150 . 2599907 . 10.1016/j.mce.2005.11.049 .

Notes and References

1. Policastro P, Ovitt CE, Hoshina M, Fukuoka H, Boothby MR, Boime I . The beta subunit of human chorionic gonadotropin is encoded by multiple genes . The Journal of Biological Chemistry . 258 . 19 . 11492–11499 . October 1983 . 6194155 . 10.1016/S0021-9258(17)44254-2 . free .
2. Web site: Entrez Gene: CGB2 chorionic gonadotropin, beta polypeptide 2.
3. Dirnhofer S, Hermann M, Hittmair A, Hoermann R, Kapelari K, Berger P . Expression of the human chorionic gonadotropin-beta gene cluster in human pituitaries and alternate use of exon 1 . The Journal of Clinical Endocrinology and Metabolism . 81 . 12 . 4212–4217 . December 1996 . 8954017 . 10.1210/jcem.81.12.8954017 . free .