2BE6: 2.0 A Crystal Structure Of The Cav1.2 Iq Domain-ca/cam Complex

Changes in activity-dependent calcium flux through voltage-gated calcium channels (Ca(V)s) drive two self-regulatory calcium-dependent feedback processes that require interaction between Ca(2+)/calmodulin (Ca(2+)/CaM) and a Ca(V) channel consensus isoleucine-glutamine (IQ) motif: calcium-dependent inactivation (CDI) and calcium-dependent facilitation (CDF). Here, we report the high-resolution structure of the Ca(2+)/CaM-Ca(V)1.2 IQ domain complex. The IQ domain engages hydrophobic pockets in the N-terminal and C-terminal Ca(2+)/CaM lobes through sets of conserved 'aromatic anchors.' Ca(2+)/N lobe adopts two conformations that suggest inherent conformational plasticity at the Ca(2+)/N lobe-IQ domain interface. Titration calorimetry experiments reveal competition between the lobes for IQ domain sites. Electrophysiological examination of Ca(2+)/N lobe aromatic anchors uncovers their role in Ca(V)1.2 CDF. Together, our data suggest that Ca(V) subtype differences in CDI and CDF are tuned by changes in IQ domain anchoring positions and establish a framework for understanding CaM lobe-specific regulation of Ca(V)s.
PDB ID: 2BE6Download
MMDB ID: 36198
PDB Deposition Date: 2005/10/23
Updated in MMDB: 2005/12
Experimental Method:
x-ray diffraction
Resolution: 2  Å
Source Organism:
Similar Structures:
Biological Unit for 2BE6: dimeric; determined by author and by software (PISA)
Molecular Components in 2BE6
Label Count Molecule
Proteins (2 molecules)
Calmodulin 2
Molecule annotation
Voltage-dependent L-type Calcium Channel Alpha-1c Subunit
Molecule annotation
Chemicals (5 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB