2QVM

The second Ca2+-binding domain of the Na+-Ca2+ exchanger is essential for regulation: crystal structures and mutational analysis


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.703 Å
  • R-Value Free: 0.219 
  • R-Value Work: 0.185 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

The second Ca2+-binding domain of the Na+ Ca2+ exchanger is essential for regulation: crystal structures and mutational analysis

Mercado Besserer, G.Ottolia, M.Nicoll, D.A.Chaptal, V.Cascio, D.Philipson, K.D.Abramson, J.

(2007) Proc.Natl.Acad.Sci.Usa 104: 18467-18472

  • DOI: 10.1073/pnas.0707417104
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • The Na(+)-Ca(2+) exchanger plays a central role in cardiac contractility by maintaining Ca(2+) homeostasis. Two Ca(2+)-binding domains, CBD1 and CBD2, located in a large intracellular loop, regulate activity of the exchanger. Ca(2+) binding to these ...

    The Na(+)-Ca(2+) exchanger plays a central role in cardiac contractility by maintaining Ca(2+) homeostasis. Two Ca(2+)-binding domains, CBD1 and CBD2, located in a large intracellular loop, regulate activity of the exchanger. Ca(2+) binding to these regulatory domains activates the transport of Ca(2+) across the plasma membrane. Previously, we solved the structure of CBD1, revealing four Ca(2+) ions arranged in a tight planar cluster. Here, we present structures of CBD2 in the Ca(2+)-bound (1.7-A resolution) and -free (1.4-A resolution) conformations. Like CBD1, CBD2 has a classical Ig fold but coordinates only two Ca(2+) ions in primary and secondary Ca(2+) sites. In the absence of Ca(2+), Lys(585) stabilizes the structure by coordinating two acidic residues (Asp(552) and Glu(648)), one from each of the Ca(2+)-binding sites, and prevents a substantial protein unfolding. We have mutated all of the acidic residues that coordinate the Ca(2+) ions and have examined the effects of these mutations on regulation of exchange activity. Three mutations (E516L, D578V, and E648L) at the primary Ca(2+) site completely remove Ca(2+) regulation, placing the exchanger into a constitutively active state. These are the first data defining the role of CBD2 as a regulatory domain in the Na(+)-Ca(2+) exchanger.


    Organizational Affiliation

    Department of Physiology, Cardiovascular Research Laboratories, and U.S. Department of Energy Institute for Genomics and Proteomics, University of California, Los Angeles, CA 90095, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Sodium/calcium exchanger 1
A
192Canis lupus familiarisMutation(s): 0 
Gene Names: SLC8A1 (NCX1)
Find proteins for P23685 (Canis lupus familiaris)
Go to Gene View: SLC8A1
Go to UniProtKB:  P23685
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

Download SDF File 
Download CCD File 
A
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.703 Å
  • R-Value Free: 0.219 
  • R-Value Work: 0.185 
  • Space Group: P 21 21 2
Unit Cell:
Length (Å)Angle (°)
a = 86.030α = 90.00
b = 59.232β = 90.00
c = 22.592γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data collection
PHASERphasing
SCALEPACKdata scaling
REFMACrefinement
DENZOdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-11-13
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance