Modelling of some potential effects of lumenal Ca2+ binding on the kinetics of Ca2+ release from the endoplasmic reticulum

Methods to Probe Calcium Regulation by BCL-2 Family Members

BCL-2 family members have additional roles beyond direct regulation of mitochondrial outer membrane permeabilization (MOMP) in apoptosis. One such important function is the release of calcium from the endoplasmic reticulum (ER), which critically contributes to the process of apoptosis. Here, we describe a protocol to measure calcium levels in the ER, mitochondria, and cytosol, with specific consideration of BCL-2 family biology.

Chemical calcium indicators

Our understanding of the underlying mechanisms of Ca2+ signaling as well as our appreciation for its ubiquitous role in cellular processes has been rapidly advanced, in large part, due to the development of fluorescent Ca2+ indicators. In this chapter, we discuss some of the most common chemical Ca2+ indicators that are widely used for the investigation of intracellular Ca2+ signaling. Advantages, limitations and relevant procedures will be presented for each dye including their spectral qualities, dissociation constants, chemical forms, loading methods and equipment for optimal imaging. Chemical indicators now available allow for intracellular Ca2+ detection over a very large range (<50 nM to >50 microM). High affinity indicators can be used to quantify Ca2+ levels in the cytosol while lower affinity indicators can be optimized for measuring Ca2+ in subcellular compartments with higher concentrations. Indicators can be classified into either single wavelength or ratiometric dyes. Both classes require specific lasers, filters, and/or detection methods that are dependent upon their spectral properties and both classes have advantages and limitations. Single wavelength indicators are generally very bright and optimal for Ca2+ detection when more than one fluorophore is being imaged. Ratiometric indicators can be calibrated very precisely and they minimize the most common problems associated with chemical Ca2+ indicators including uneven dye loading, leakage, photobleaching, and changes in cell volume. Recent technical advances that permit in vivo Ca2+ measurements will also be discussed.