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Amino acids 356–372 constitute a G i ‐activator sequence of the α 2 ‐adrenergic receptor and have a Phe substitute in the G protein‐activator sequence motif
Author(s) -
Ikezu Tsuneya,
Okamoto Takashi,
Ogata Etsuro,
Nishimoto Ikuo
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)81359-t
Subject(s) - peptide , peptide sequence , residue (chemistry) , stereochemistry , activator (genetics) , chemistry , receptor , amino acid , biochemistry , gene
The human α 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 α 2 ‐F) was found to activate G i and G o strongly with a saturated effect at 1–3 μM. Furthermore, the substitution of the C‐terminal Phe of peptide α 2 ‐F with Arg, Trp, and Tyr (but not Ala or Asp) did not appreciably affect the G i ‐activating potency. It is suggested that the C‐terminal basic residue of the B‐B‐X‐X‐B motif in G i ‐activating sequences can be replaced by an aromatic residue.