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Biochem Biophys Res Commun. 2015 Jul 17-24;463(1-2):64-9. doi: 10.1016/j.bbrc.2015.05.018. Epub 2015 May 16.

Biochemical characterization of a heterotrimeric G(i)-protein activator peptide designed from the junction between the intracellular third loop and sixth transmembrane helix in the m4 muscarinic acetylcholine receptor.

Author information

1
Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma, 376-8515, Japan. Electronic address: terawaki@gunma-u.ac.jp.
2
Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma, 376-8515, Japan.
3
Department of Biochemistry, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa, 252-0374, Japan.

Abstract

Muscarinic acetylcholine receptors (mAChRs) are G-protein coupled receptors (GPCRs) that are activated by acetylcholine released from parasympathetic nerves. The mAChR family comprises 5 subtypes, m1-m5, each of which has a different coupling selectivity for heterotrimeric GTP-binding proteins (G-proteins). m4 mAChR specifically activates the Gi/o family by enhancing the guanine nucleotide exchange factor (GEF) reaction with the Gα subunit through an interaction that occurs via intracellular segments. Here, we report that the m4 mAChR mimetic peptide m4i3c(14)Gly, comprising 14 residues in the junction between the intracellular third loop (i3c) and transmembrane helix VI (TM-VI) extended with a C-terminal glycine residue, presents GEF activity toward the Gi1 α subunit (Gαi1). The m4i3c(14)Gly forms a stable complex with guanine nucleotide-free Gαi1 via three residues in the VTI(L/F) motif, which is conserved within the m2/4 mAChRs. These results suggest that this m4 mAChR mimetic peptide, which comprises the amino acid of the mAChR intracellular segments, is a useful tool for understanding the interaction between GPCRs and G-proteins.

KEYWORDS:

GPCR; Gαi1; Mimetic peptide; Muscarinic acetylcholine receptor

PMID:
25986737
DOI:
10.1016/j.bbrc.2015.05.018
[Indexed for MEDLINE]

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