choriogonadotropin subunit beta 3 (CGB3, CGB5, CGB8)

Function

• beta subunit of chorionic gonadotropin (hCG)
• role for pregnancy & maternal adaptation
• stimulates ovaries to synthesize the steroids essential for maintenance of pregnancy

Structure

• belongs to the glycoprotein hormones subunit beta family
• subunit of chorionic gonadotropin, a heterodimer of a common alpha chain identical to LH, FSH, TSH & hCG & a unique beta chain distinct in each of the hormones

Compartment

secreted

Alternative splicing

named isoforms=2

Expression

• high expression in the placenta throughout pregnancy
  • peak expression during the first trimester

Genetics

• gene is ncoded by a cluster of genes that have evolved by duplication from LHB
• hCG-beta is encoded by six non-allelic genes (CGB) clustered on chromosome 19q13.3 & named CGB1, CGB2, CGB3, CGB5, CGB7 & CGB8
• 2 specific CGB proteins that differ by 3 amino acids in positions 2,4 & 117 have been described:
  • type 1 (CGB7) & type 2 (CGB3, CGB5, CGB8)

Pharmacology

• available under the names Novarel (ferring) & Profasi (serono)
• used as adjunctive therapy in the treatment of obesity
• there is no substantial evidence that it facilitates weight reduction beyond that resulting from caloric restriction, that it causes a more attractive or 'normal' distribution of fat, or that it decreases the hunger & discomfort associated with calorie-restricted diets

More general terms

• chorionic gonadotropin [cG]-beta chain (CG-beta, beta-hcG, CGB)

Component of

• chorionic gonadotropin; choriogonadotropin (APL, hCG)

Database

• OMIM: https://mirror.omim.org/entry/118860
• OMIM: https://mirror.omim.org/entry/608825
• OMIM: https://mirror.omim.org/entry/608827
• UniProt: http://www.uniprot.org/uniprot/P0DN86.html