scholarly journals Themes and Variations in Endoplasmic Reticulum Calcium Release Channels: Structure and Function

2012 ◽  
Vol 52 (6) ◽  
pp. 266-271
Author(s):  
Masahiro Enomoto ◽  
Noboru Ishiyama ◽  
Min-Duk Seo ◽  
Fernando J. Amador ◽  
Peter B. Stathopulos ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Calcium Release ◽  
Structure And Function ◽  
Calcium Release Channels ◽  
Endoplasmic Reticulum Calcium ◽  
And Function

Themes and Variations in ER/SR Calcium Release Channels: Structure and Function

Physiology ◽  
2012 ◽  
Vol 27 (6) ◽  
pp. 331-342 ◽  
Author(s):  
Peter B. Stathopulos ◽  
Min-duk Seo ◽  
Masahiro Enomoto ◽  
Fernando J. Amador ◽  
Noboru Ishiyama ◽  
...  
Keyword(s):  
Calcium Release ◽  
Common Ancestor ◽  
Structural Data ◽  
Structure And Function ◽  
Release Channel ◽  
Calcium Release Channels ◽  
Channel Function ◽  
Regulatory Signal ◽  
And Function ◽  
Sr Calcium Release

Calcium (Ca2+) release from reticular stores is a vital regulatory signal in eukaryotes. Recent structural data on large NH2-terminal regions of IP3Rs and RyRs and their tetrameric arrangement in the full-length context reveal striking mechanistic similarities in Ca2+ release channel function. A common ancestor found in unicellular genomes underscores the fundamentality of these elements to Ca2+ release channels.

Oxidative protein folding in the mammalian endoplasmic reticulum

2004 ◽  
Vol 32 (5) ◽  
pp. 655-658 ◽  
Author(s):  
C.E. Jessop ◽  
S. Chakravarthi ◽  
R.H. Watkins ◽  
N.J. Bulleid
Keyword(s):  
Endoplasmic Reticulum ◽  
Mammalian Cells ◽  
Redox State ◽  
Structure And Function ◽  
Reduced Form ◽  
Secretory Proteins ◽  
Oxidative Protein Folding ◽  
Disulphide Bonds ◽  
And Function ◽  
Substrate Proteins

Native disulphide bonds are essential for the structure and function of many membrane and secretory proteins. Disulphide bonds are formed, reduced and isomerized in the endoplasmic reticulum of mammalian cells by a family of oxidoreductases, which includes protein disulphide isomerase (PDI), ERp57, ERp72, P5 and PDIR. This review will discuss how these enzymes are maintained in either an oxidized redox state that allows them to form disulphide bonds in substrate proteins or a reduced form that allows them to perform isomerization and reduction reactions, how these opposing pathways may co-exist within the same compartment and why so many oxidoreductases exist when PDI alone can perform all three of these functions.

Heterologous expression of polycystin-1 inhibits endoplasmic reticulum calcium leak in stably transfected MDCK cells

2008 ◽  
Vol 294 (6) ◽  
pp. F1279-F1286 ◽  
Author(s):  
Kimberly H. Weber ◽  
Eun Kyung Lee ◽  
Uma Basavanna ◽  
Sabina Lindley ◽  
Roy C. Ziegelstein ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Calcium Release ◽  
Mdck Cells ◽  
Calcium Ionophore ◽  
Calcium Flux ◽  
Calcium Stores ◽  
Endoplasmic Reticulum Calcium ◽  
Calcium Indicator ◽  
Luminal Calcium ◽  
Er Membrane

We previously found that polycystin-1 accelerated the decay of ligand-activated cytoplasmic calcium transients through enhanced reuptake of calcium into the endoplasmic reticulum (ER; Hooper KM, Boletta A, Germino GG, Hu Q, Ziegelstein RC, Sutters M. Am J Physiol Renal Physiol 289: F521–F530, 2005). Calcium flux across the ER membrane is determined by the balance of active uptake and passive leak. In the present study, we show that polycystin-1 inhibited calcium leak across the ER membrane, an effect that would explain the capacity of this protein to accelerate clearance of calcium from the cytoplasm following a calcium release response. Calcium leak was detected by measurement of the accumulation of calcium in the cytoplasm following treatment with thapsigargin. Heterologous polycystin-1, stably expressed in Madin-Darby canine kidney cells, attenuated the thapsigargin-induced calcium peak with no effect on basal calcium stores, mitochondrial calcium uptake, or extrusion of calcium across the plasma membrane. The capacity of polycystin-1 to limit the rate of decay of ER luminal calcium following inhibition of the pump was shown indirectly using the calcium ionophore ionomycin, and directly by loading the ER with a low-affinity calcium indicator. We conclude that disruption of ER luminal calcium homeostasis may contribute to the cyst phenotype in autosomal dominant polycystic kidney disease.

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