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PDBsum entry 1vry
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Membrane protein
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PDB id
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1vry
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References listed in PDB file
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Key reference
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Title
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Structure and dynamics of the second and third transmembrane domains of human glycine receptor.
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Authors
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D.Ma,
Z.Liu,
L.Li,
P.Tang,
Y.Xu.
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Ref.
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Biochemistry, 2005,
44,
8790-8800.
[DOI no: ]
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PubMed id
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Abstract
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A 61-residue polypeptide resembling the second and third transmembrane domains
(TM23) of the alpha-1 subunit of human glycine receptor and its truncated form,
both with the wild-type loop linking the two TM domains (the "23" loop), were
studied using high-resolution NMR. Well-defined domain structures can be
identified for the TM2, 23 loop, and TM3 regions. Contrary to the popular model
of a long and straight alpha-helical structure for the pore-lining TM2 domain
for the Cys-loop receptor family, the last three residues of the TM2 domain and
the first eight residues of the 23 loop (S16-S26) seem to be intrinsically
nonhelical and highly flexible even in trifluoroethanol, a solvent known to
promote and stabilize alpha-helical structures. The six remaining residues of
the 23 loop and most of the TM3 domain exhibit helical structures with a kinked
pi-helix (or a pi-turn) from W34 to C38 and a kink angle of 159 +/- 3 degrees .
The tertiary fold of TM3 relative to TM2 is defined by several unambiguously
identified long-range NOE cross-peaks within the loop region and between TM2 and
TM3 domains. The 20 lowest-energy structures show a left-handed tilt of TM3
relative to TM2 with a tilting angle of 44 +/- 2 degrees between TM2 (V1-Q14)
and TM3 (L39-E48) helix axes. This left-handed TM2-TM3 arrangement ensures a
neatly packed right-handed quaternary structure of five subunits to form an
ion-conducting pore. This is the first time that two TM domains of the glycine
receptor linked by the important 23 loop have ever been analyzed at atomistic
resolution. Many structural characteristics of the receptor can be inferred from
the structural and dynamical features identified in this study.
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