Analysis of the three dimensional structure of the CXGXC motif in the CMGCC and CAGYC regions of α- and β-subunits of human chorionic gonadotropin: Importance of glycine residue (G) in the motif

Kengo Kinoshita, Masami Kusunoki, Kiyoshi Miyai

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

The three dimensional structures of the C 1X 2G 3(X 3)X 4C 5 motif of hCG, which is considered to be important for noncovalent assembly of the α- and β-subunits of glycoprotein hormones were analyzed to assess the importance of glycine (Gly) (G) at site X 3 in the motif by the conformational energy calculation using computational procedures. In the C 1M 2G 3(X 3)C 4C 5 motif of the α-subunit, Ramachandran plot analysis showing the allowed area of the dihedral angles demonstrated that only a Gly residue was allowed at site X 3. In calculating collision with surrounding atoms as a monomer the possible main chain models of the C 1A 2G 3(X 3)Y 4C 5 motif in the β-subunit showed that only alanine (Ala) (A) or Gly at site X 3 is allowed to alleviate the collision with the cysteine (Cys) (C) residues which form a disulfide bridge. A mutant of the β-subunit with the C 1A 2A 3(X 3)Y 4C 5 motif (Ala at site X 3) may not compose a heterodimer with the α-subunit because of interference of intermolecular hydrogen bond formation. These findings indicate that the Gly residue at site X 3 (G 3) in the motif is essential for heterodimer formation of glycoprotein hormones. The significance of similar motifs found in various human proteins other than glycoprotein hormones was suggested.

Original languageEnglish
Pages (from-to)51-58
Number of pages8
Journalendocrine journal
Volume53
Issue number1
DOIs
Publication statusPublished - 2006
Externally publishedYes

Keywords

  • CXGXC motif
  • Glycoprotein hormones
  • Ramachandran plot analysis
  • TSH deficiency
  • hCG

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

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