Retrograde activation of store-operated calcium channel.
Store-operated Ca2+ entry represents an important mechanism for refilling of a depleted intracellular-reticulum Ca2+ store following sustained activation of the IP3 receptor or ryanodine receptor RyR/Ca2+ release channel in the endoplasmic/sarcoplasmic reticulum (ER/SR). Recent studies have demonstrated the existence of store-operated Ca2+ channel (SOC) in muscle cells, whose activation process appears to be coupled to conformational changes of the RyR. Regulation of the plasma membrane (PM)-resided SOC by the SR-located RyR requires an integrity of the junctional membrane structure between SR and PM. Proteins that interact with RyR or influence the Ca2+ buffering capacity in the ER or SR lumen also participate in the activation process of SOC. Calsequestrin (CSQ) and calreticulin (CRT) are SR/ER-resident proteins, with highly negative charged regions at the carboxyl-terminal end that exhibit high buffering capacity for luminal Ca2+. CSQ and CRT not only modulate the intracellular Ca2+ release process but also might provide retrograde signals to regulate the function of SOC. The functional interplay between CSQ, RyR and SOC may serve essential roles of Ca2+ signaling in muscle contraction and development. A tight link between the expression of CRT and operation of SOC exist in certain cancer cells, where the reduced sensitivity to apoptosis may correlate with the altered function of SOC.
Ma
Jianjie
J
Department of Physiology and Biophysics, UMDNJ-Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA. maj2@umdnj.edu
Pan
Zui
Z
D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D037282:Calreticulin / Q000378:metabolism*; D002155:Calsequestrin / Q000378:metabolism*; D006801:Humans; D015640:Ion Channel Gating; D008969:Molecular Sequence Data; D032342:Muscle Cells / Q000378:metabolism; D012433:Ryanodine / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
D037282:Calreticulin; D002155:Calsequestrin; D019837:Ryanodine Receptor Calcium Release Channel; D012433:Ryanodine; D002118:Calcium