Amino acids 356-372 constitute a Gi-activator sequence of the alpha 2-adrenergic receptor and have a Phe substitute in the G protein-activator sequence motif

FEBS Lett. 1992 Oct 12;311(1):29-32. doi: 10.1016/0014-5793(92)81359-t.


The human alpha 2-adrenergic receptor contains the sequence KASRWRGRQNREKRFTF (amino acids 356-372) at the C-terminal end of its third intracellular loop. This sequence satisfies the structural criteria for G protein-activating sequences [(1992) J. Biol. Chem. 267, 8342-8346] except that the C-terminal sequence is B-B-X-X-Phe instead of B-B-X-B or B-B-X-X-B (B: basic residue, X: non-basic residue). Nevertheless, the synthetic peptide corresponding to this sequence (peptide alpha 2-F) was found to activate Gi and Go strongly with a saturated effect at 1-3 microM. Furthermore, the substitution of the C-terminal Phe of peptide alpha 2-F with Arg, Trp, and Tyr (but not Ala or Asp) did not appreciably affect the Gi-activating potency. It is suggested that the C-terminal basic residue of the B-B-X-X-B motif in Gi-activating sequences can be replaced by an aromatic residue.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Conserved Sequence
  • Dose-Response Relationship, Drug
  • GTP-Binding Proteins / metabolism*
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • Models, Biological
  • Molecular Sequence Data
  • Peptide Fragments / chemical synthesis
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism*
  • Phenylalanine
  • Protein Binding
  • Receptors, Adrenergic, alpha / genetics
  • Receptors, Adrenergic, alpha / metabolism*
  • Signal Transduction*


  • Peptide Fragments
  • Receptors, Adrenergic, alpha
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • Phenylalanine
  • GTP-Binding Proteins