Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
EMBO J. 1999 Sep 1;18(17):4733-43.

Steady-state free Ca(2+) in the yeast endoplasmic reticulum reaches only 10 microM and is mainly controlled by the secretory pathway pump pmr1.

Author information

  • 1Institut f√ľr Biochemie der Universit√§t Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany.

Abstract

Over recent decades, diverse intracellular organelles have been recognized as key determinants of Ca(2+) signaling in eukaryotes. In yeast however, information on intra-organellar Ca(2+) concentrations is scarce, despite the demonstrated importance of Ca(2+) signals for this microorganism. Here, we directly monitored free Ca(2+) in the lumen of the endoplasmic reticulum (ER) of yeast cells, using a specifically targeted version of the Ca(2+)-sensitive photoprotein aequorin. Ca(2+) uptake into the yeast ER displayed characteristics distinctly different from the mammalian ER. At steady-state, the free Ca(2+) concentration in the ER lumen was limited to approximately 10 microM, and ER Ca(2+) sequestration was insensitive to thapsigargin, an inhibitor specific for mammalian ER Ca(2+) pumps. In pmr1 null mutants, free Ca(2+) in the ER was reduced by 50%. Our findings identify the secretory pathway pump Pmr1, predominantly localized in the Golgi, as a major component of ER Ca(2+) uptake activity in yeast.

PMID:
10469652
[PubMed - indexed for MEDLINE]
PMCID:
PMC1171546
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk