Calcium Influx Factor Is Synthesized by Yeast and Mammalian Cells Depleted of Organellar Calcium Stores

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 96; no. 1; pp. 121 - 126
• Main Authors: Csutora, Peter, Su, Zhengchang, Kim, Hak Yong, Bugrim, Andrej, Cunningham, Kyle W., Nuccitelli, Richard, Keizer, Joel E., Hanley, Michael R., Blalock, J. Edwin, Marchase, Richard B.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 05.01.1999; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences
• Subjects: Animal cells; Animals; Biological Factors - biosynthesis; Biological Sciences; Biological Transport; Calcium; Calcium - metabolism; Calcium Signaling; Cell Compartmentation; Cell lines; Cell membranes; Cells; Cellular biology; Diffusion; Endoplasmic Reticulum - metabolism; Fluorescence; Humans; Inositol 1,4,5-Trisphosphate - metabolism; Ion Channel Gating; Jurkat Cells; Oocytes; Patch-Clamp Techniques; Pipettes; Species Specificity; T lymphocytes; Xenopus laevis; Yeast; Yeasts
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.96.1.121

Depletion of endoplasmic reticulum Ca2+stores leads to the entry of extracellular Ca2+into the cytoplasm, a process termed capacitative or store-operated Ca2+entry. Partially purified extracts were prepared from the human Jurkat T lymphocyte cell line and yeast in which Ca2+stores were depleted by chemical and genetic means, respectively. After microinjection into Xenopus laevis oocytes, the extracts elicited a wave of increased cytoplasmic free Ca2+([Ca2+]i) that spread from the point of injection across the oocyte. Extracts from cells with replete organellar Ca2+stores were inactive. The increases depended on extracellular Ca2+, were unaffected by the inositol 1,4,5-trisphosphate (IP3) inhibitor heparin or an anti-IP3receptor antibody and were unchanged when the endoplasmic reticulum was segregated to the hemisphere opposite the injection site by centrifugation. Confocal microscopy revealed that [Ca2+]iincreases were most pronounced at the periphery of the oocyte. The patterns of [Ca2+]iincreases were replicated by computer simulations based on a diffusible messenger of about 700 Da that directly activates Ca2+influx. In addition, ICRAC, a Ca2+release-activated Ca2+current monitored in Jurkat cells by whole-cell patch clamp recordings, was more rapidly activated when active extracts were included in the patch pipette than by the inclusion of a Ca2+chelator or IP3. These data support the existence in yeast and mammalian cells depleted of Ca2+stores of a functionally conserved diffusible calcium influx factor that directly activates Ca2+influx.