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PDBsum entry 4zw2
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Metal transport
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PDB id
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4zw2
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References listed in PDB file
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Key reference
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Title
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Structural and biophysical analyses of the skeletal dihydropyridine receptor β subunit β1areveal critical roles of domain interactions for stability.
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Authors
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N.C.Norris,
S.Joseph,
S.Aditya,
Y.Karunasekara,
P.G.Board,
A.F.Dulhunty,
A.J.Oakley,
M.G.Casarotto.
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Ref.
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J Biol Chem, 2017,
292,
8401-8411.
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PubMed id
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Abstract
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Excitation-contraction (EC) coupling in skeletal muscle requires a physical
interaction between the voltage-gated calcium channel dihydropyridine receptor
(DHPR) and the ryanodine receptor Ca2+release channel. Although the
exact molecular mechanism that initiates skeletal EC coupling is unresolved, it
is clear that both the α1and β subunits of DHPR are essential for
this process. Here, we employed a series of techniques, including size-exclusion
chromatography-multi-angle light scattering, differential scanning fluorimetry,
and isothermal calorimetry, to characterize various biophysical properties of
the skeletal DHPR β subunit β1aRemoval of the intrinsically
disordered N and C termini and the hook region of β1aprevented
oligomerization, allowing for its structural determination by X-ray
crystallography. The structure had a topology similar to that of previously
determined β isoforms, which consist of SH3 and guanylate kinase domains.
However, transition melting temperatures derived from the differential scanning
fluorimetry experiments indicated a significant difference in stability of
∼2-3 °C between the β1aand β2aconstructs, and the
addition of the DHPR α1sI-II loop (α-interaction domain) peptide
stabilized both β isoforms by ∼6-8 °C. Similar to other β isoforms,
β1abound with nanomolar affinity to the α-interaction domain, but
binding affinities were influenced by amino acid substitutions in the adjacent
SH3 domain. These results suggest that intramolecular interactions between the
SH3 and guanylate kinase domains play a role in the stability of
β1awhile also providing a conduit for allosteric signaling events.
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