Apo-Calmodulin Binds with its C-terminal Domain to the N-Methyl-D-aspartate Receptor NR1 C0 Region

Zeynep Akyol, Jason A. Bartos, Michelle A. Merrill, Laurel A. Faga, Olav R. Jaren, Madeline A. Shea, Johannes W Hell

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

Calmodulin (CaM) is the major Ca2+ sensor in eukaryotic cells. It consists of four EF-hand Ca2+ binding motifs, two in its N-terminal domain and two in its C-terminal domain. Through a negative feedback loop, CaM inhibits Ca2+ influx through N-methyl-D-aspartate-type glutamate receptors in neurons by binding to the C0 region in the cytosolic tail of the NR1 subunit. Ca2+-depleted (apo)CaM is pre-associated with a variety of ion channels for fast and effective regulation of channel activities upon Ca2+ influx. Using the NR1 C0 region for fluorescence and circular dichroism spectroscopy studies we found that not only Ca2+-saturated CaM but also apoCaM bound to NR1 C0. In vitro interaction assays showed that apoCaM also binds specifically to full-length NR1 solubilized from rat brain and to the complete C terminus of the NR1 splice form that contains the C0 plus C2′ domain. The Ca 2+-independent interaction of CaM was also observed with the isolated C- but not N-terminal fragment of calmodulin in the independent spectroscopic assays. Fluorescence polarization studies indicated that apoCaM associated via its C-terminal domain with NR1 C0 in an extended conformation and collapsed to adopt a more compact conformation of faster rotational mobility in its complex with NR1 C0 upon addition of Ca2+. Our results indicate that apoCaM is associated with NR1 and that the complex of CaM bound to NR1 C0 undergoes a dramatic conformational change when Ca2+ binds to CaM.

Original languageEnglish (US)
Pages (from-to)2166-2175
Number of pages10
JournalJournal of Biological Chemistry
Volume279
Issue number3
DOIs
StatePublished - Jan 16 2004
Externally publishedYes

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Calmodulin
N-Methyl-D-Aspartate Receptors
Conformations
Assays
Fluorescence
Circular dichroism spectroscopy
EF Hand Motifs
Fluorescence Polarization
Glutamate Receptors
Eukaryotic Cells
N-Methylaspartate
Circular Dichroism
Ion Channels
Neurons
Tail
Rats
Brain
Spectrum Analysis
Polarization
Feedback

ASJC Scopus subject areas

  • Biochemistry

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Apo-Calmodulin Binds with its C-terminal Domain to the N-Methyl-D-aspartate Receptor NR1 C0 Region. / Akyol, Zeynep; Bartos, Jason A.; Merrill, Michelle A.; Faga, Laurel A.; Jaren, Olav R.; Shea, Madeline A.; Hell, Johannes W.

In: Journal of Biological Chemistry, Vol. 279, No. 3, 16.01.2004, p. 2166-2175.

Research output: Contribution to journalArticle

Akyol, Zeynep ; Bartos, Jason A. ; Merrill, Michelle A. ; Faga, Laurel A. ; Jaren, Olav R. ; Shea, Madeline A. ; Hell, Johannes W. / Apo-Calmodulin Binds with its C-terminal Domain to the N-Methyl-D-aspartate Receptor NR1 C0 Region. In: Journal of Biological Chemistry. 2004 ; Vol. 279, No. 3. pp. 2166-2175.
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abstract = "Calmodulin (CaM) is the major Ca2+ sensor in eukaryotic cells. It consists of four EF-hand Ca2+ binding motifs, two in its N-terminal domain and two in its C-terminal domain. Through a negative feedback loop, CaM inhibits Ca2+ influx through N-methyl-D-aspartate-type glutamate receptors in neurons by binding to the C0 region in the cytosolic tail of the NR1 subunit. Ca2+-depleted (apo)CaM is pre-associated with a variety of ion channels for fast and effective regulation of channel activities upon Ca2+ influx. Using the NR1 C0 region for fluorescence and circular dichroism spectroscopy studies we found that not only Ca2+-saturated CaM but also apoCaM bound to NR1 C0. In vitro interaction assays showed that apoCaM also binds specifically to full-length NR1 solubilized from rat brain and to the complete C terminus of the NR1 splice form that contains the C0 plus C2′ domain. The Ca 2+-independent interaction of CaM was also observed with the isolated C- but not N-terminal fragment of calmodulin in the independent spectroscopic assays. Fluorescence polarization studies indicated that apoCaM associated via its C-terminal domain with NR1 C0 in an extended conformation and collapsed to adopt a more compact conformation of faster rotational mobility in its complex with NR1 C0 upon addition of Ca2+. Our results indicate that apoCaM is associated with NR1 and that the complex of CaM bound to NR1 C0 undergoes a dramatic conformational change when Ca2+ binds to CaM.",
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AU - Akyol, Zeynep

AU - Bartos, Jason A.

AU - Merrill, Michelle A.

AU - Faga, Laurel A.

AU - Jaren, Olav R.

AU - Shea, Madeline A.

AU - Hell, Johannes W

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