Bax inhibitor-1 Is Likely a pH-sensitive Calcium Leak Channel, Not a H+/Ca2+ Exchanger

Sci Signal. 2014 Sep 16;7(343):pe22. doi: 10.1126/scisignal.2005764.


The endoplasmic reticulum (ER) plays a key role in the synthesis, folding, and sorting of proteins, and disturbances of this delicate system can cause cell death. The ER also serves as the major intracellular calcium (Ca(2+)) store, and release of Ca(2+) from this store controls diverse cellular functions. At the interface of both these functions of the ER is Bax inhibitor-1 (BI-1), an evolutionarily conserved multifunctional protein that mediates Ca(2+) efflux from the ER and protects against ER stress. Several mechanisms have been proposed to explain how BI-1 might mediate Ca(2+) efflux from the ER. Chang et al. present structural evidence that a bacterial homolog of BI-1, BsYetJ, is a pH-sensitive Ca(2+) leak channel. This finding not only sheds a new light on ER Ca(2+) efflux mediated by BI-1, but also provides a tentative function for other members of the BI-1 protein family.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis Regulatory Proteins / metabolism*
  • Bacillus subtilis / genetics
  • Bacillus subtilis / metabolism*
  • Calcium / metabolism*
  • Calcium Channels / metabolism*
  • Cell Membrane / metabolism*
  • Endoplasmic Reticulum / metabolism*
  • Humans
  • Hydrogen-Ion Concentration
  • Membrane Proteins / metabolism*
  • Models, Biological
  • Proteolipids / metabolism*
  • Species Specificity


  • Apoptosis Regulatory Proteins
  • Calcium Channels
  • Membrane Proteins
  • Proteolipids
  • TMBIM6 protein, human
  • proteoliposomes
  • Calcium