Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2009 Jul 1;587(Pt 13):3091-4.
doi: 10.1113/jphysiol.2009.172049.

Cardiac calsequestrin: quest inside the SR

Sandor Györke  1 , Sarah C W Stevens, Dmitry Terentyev
Affiliations
Review

Cardiac calsequestrin: quest inside the SR

Sandor Györke et al. J Physiol. .
No abstract available

PubMed Disclaimer

Figures

Figure 1
Figure 1. Ca2+ handling in myocytes from normal hearts and hearts lacking CASQ2
In a normal myocyte, Ca2+ release from the SR evoked by Ca2+ entry through voltage-dependent Ca2+ channels (LCCs) results in a decline of [Ca2+] in the SR. As [Ca2+]SR declines, Ca2+ dissociates from CASQ2 and the Ca2+-free CASQ2 monomers bind to and inhibit RyR2s causing Ca2+ release to terminate at a certain threshold [Ca2+]SR. The SR Ca2+ store stays refractory for some time after luminal Ca2+ is recovered by the SERCA2 pump and Ca2+-bound CASQ2 dissociates from TRD. This prevents spontaneous Ca2+ release during diastole. In myocytes lacking CASQ2, reduced SR Ca2+ binding capacity is compensated by increased SR Ca2+ volume. In the absence of the inhibitory influence of CASQ2 increased leak through the RyR2 results in reduced basal [Ca2+]SR. In addition, the RyR2s lack the capacity to deactivate until nearly complete depletion stops CICR and store refractoriness is substantially shortened predisposing the SR to premature SR Ca2+ release. Extrasystolic elevation of [Ca2+]c evokes pro-arrhythmic delayed afterdepolarizations (DADs) by stimulating the Na+/Ca2+ exchanger (NCX).
See this image and copyright information in PMC

Comment in

Comment on

References

    1. Bassani JW, Bassani RA, Bers DM. Twitch-dependent SR Ca accumulation and release in rabbit ventricular myocytes. Am J Physiol Cell Physiol. 1993;265:C533–C540. - PubMed
    1. Bers DM. Excitation-Contraction Coupling and Cardiac Contractile Force. The Netherlands: Kluwer Academic Publishers; 2001.
    1. Delbridge LM, Satoh H, Yuan W, Bassani JW, Qi M, Ginsburg KS, Samarel AM, Bers DM. Cardiac myocyte volume, Ca2+ fluxes, and sarcoplasmic reticulum loading in pressure-overload hypertrophy. Am J Physiol Heart Circ Physiol. 1997;272:H2425–H2435. - PubMed
    1. Eldar M, Pras E, Lahat H. A missense mutation in the CASQ2 gene is associated with autosomal-recessive catecholamine-induced polymorphic ventricular tachycardia. Trends Cardiovasc Med. 2003;13:148–151. - PubMed
    1. Endo M. Conditions required for calcium-induced release of calcium from the sarcoplasmic reticulum. Proc Jpn Acad. 1975;51:467–472.