scholarly journals Endoplasmic reticulum–plasma membrane contacts: Principals of phosphoinositide and calcium signaling

2020 ◽  
Vol 63 ◽  
pp. 125-134 ◽  
Author(s):  
Christopher J. Stefan
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Calcium Signaling ◽  
Membrane Contacts

scholarly journals ER–Mitochondria contact sites: A new regulator of cellular calcium flux comes into play

2016 ◽  
Vol 214 (4) ◽  
pp. 367-370 ◽  
Author(s):  
Michiel Krols ◽  
Geert Bultynck ◽  
Sophie Janssens
Keyword(s):  
Endoplasmic Reticulum ◽  
Calcium Signaling ◽  
Calcium Pump ◽  
Calcium Flux ◽  
Mitochondrial Calcium ◽  
Mitochondrial Bioenergetics ◽  
Cellular Calcium ◽  
Contact Sites ◽  
Cell Biol ◽  
Membrane Contacts

Endoplasmic reticulum (ER)–mitochondria membrane contacts are hotspots for calcium signaling. In this issue, Raturi et al. (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201512077) show that the thioredoxin TMX1 inhibits the calcium pump SERCA2b at ER–mitochondria contact sites, thereby affecting ER–mitochondrial calcium transfer and mitochondrial bioenergetics.

scholarly journals Junctophilins: Key Membrane Tethers in Muscles and Neurons

2021 ◽  
Vol 14 ◽  
Author(s):  
Christopher A. Piggott ◽  
Yishi Jin
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Calcium Signaling ◽  
Deep Understanding ◽  
Evolutionary Conservation ◽  
Excitable Cells ◽  
Contraction Coupling ◽  
Functional Studies ◽  
Store Operated Calcium Entry ◽  
Membrane Tethers

Contacts between the endoplasmic reticulum (ER) and plasma membrane (PM) contain specialized tethering proteins that bind both ER and PM membranes. In excitable cells, ER–PM contacts play an important role in calcium signaling and transferring lipids. Junctophilins are a conserved family of ER–PM tethering proteins. They are predominantly expressed in muscles and neurons and known to simultaneously bind both ER- and PM-localized ion channels. Since their discovery two decades ago, functional studies using junctophilin-deficient animals have provided a deep understanding of their roles in muscles and neurons, including excitation-contraction coupling, store-operated calcium entry (SOCE), and afterhyperpolarization (AHP). In this review, we highlight key findings from mouse, fly, and worm that support evolutionary conservation of junctophilins.

Triple Fixation For Electron Microscopy

1968 ◽  
Vol 26 ◽  
pp. 90-91 ◽  
Author(s):  
M. A. Hayat
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Electron Beam ◽  
Plasma Membrane ◽  
Myelin Sheath ◽  
Good Deal ◽  
Granular Structure ◽  
Oxidizing Agent ◽  
Fixation Technique ◽  
Large Clusters

Potassium permanganate has been successfully employed to study membranous structures such as endoplasmic reticulum, Golgi, plastids, plasma membrane and myelin sheath. Since KMnO4 is a strong oxidizing agent, deposition of manganese or its oxides account for some of the observed contrast in the lipoprotein membranes, but a good deal of it is due to the removal of background proteins either by dehydration agents or by volatalization under the electron beam. Tissues fixed with KMnO4 exhibit somewhat granular structure because of the deposition of large clusters of stain molecules. The gross arrangement of membranes can also be modified. Since the aim of a good fixation technique is to preserve satisfactorily the cell as a whole and not the best preservation of only a small part of it, a combination of a mixture of glutaraldehyde and acrolein to obtain general preservation and KMnO4 to enhance contrast was employed to fix plant embryos, green algae and fungi.

scholarly journals Synaptotagmins at the endoplasmic reticulum–plasma membrane contact sites maintain diacylglycerol homeostasis during abiotic stress

2021 ◽  
Author(s):  
Noemi Ruiz-Lopez ◽  
Jessica Pérez-Sancho ◽  
Alicia Esteban del Valle ◽  
Richard P Haslam ◽  
Steffen Vanneste ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Abiotic Stress ◽  
Fluorescent Protein ◽  
Mechanical Damage ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Membrane Contact ◽  
Green Fluorescent

Abstract Endoplasmic reticulum-plasma membrane contact sites (ER-PM CS) play fundamental roles in all eukaryotic cells. Arabidopsis thaliana mutants lacking the ER-PM protein tether synaptotagmin1 (SYT1) exhibit decreased plasma membrane (PM) integrity under multiple abiotic stresses such as freezing, high salt, osmotic stress and mechanical damage. Here, we show that, together with SYT1, the stress-induced SYT3 is an ER-PM tether that also functions in maintaining PM integrity. The ER-PM CS localization of SYT1 and SYT3 is dependent on PM phosphatidylinositol-4-phosphate and is regulated by abiotic stress. Lipidomic analysis revealed that cold stress increased the accumulation of diacylglycerol at the PM in a syt1/3 double mutant relative to wild type while the levels of most glycerolipid species remain unchanged. Additionally, the SYT1-green fluorescent protein (GFP) fusion preferentially binds diacylglycerol in vivo with little affinity for polar glycerolipids. Our work uncovers a SYT-dependent mechanism of stress adaptation counteracting the detrimental accumulation of diacylglycerol at the PM produced during episodes of abiotic stress.

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