Limits...
Palmitoylation of the Na/Ca exchanger cytoplasmic loop controls its inactivation and internalization during stress signaling.

Reilly L, Howie J, Wypijewski K, Ashford ML, Hilgemann DW, Fuller W - FASEB J. (2015)

Bottom Line: Surprisingly, palmitoylation does not influence trafficking or localization of NCX1 to surface membranes, nor does it strongly affect the normal forward or reverse transport modes of NCX1.However, exchangers that cannot be palmitoylated do not inactivate normally (leading to substantial activity in conditions when wild-type exchangers are inactive) and do not promote cargo-dependent endocytosis that internalizes 50% of the cell surface following strong G-protein activation or large Ca transients.The palmitoylated cysteine in NCX1 is found in all vertebrate and some invertebrate NCX homologs.

View Article: PubMed Central - PubMed

Affiliation: *Division of Cardiovascular and Diabetes Medicine, Medical Research Institute, College of Medicine, Dentistry, and Nursing, University of Dundee, Dundee, United Kingdom; and Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

No MeSH data available.


Related in: MedlinePlus

Effect of palmitoylation on NCX1 inactivation by Ca depletion and excess. Stably transfected FT-293 cells expressing WT and C739A NCX1 were voltage clamped in the whole-cell mode. Current traces are shown in red, capacitance traces in blue, and changes in extracellular Ca indicated in green. Outward NCX1 currents were activated by stepping extracellular Ca from 0 to 4 mM in cells expressing WT (left) and C739A exchangers (center). A) Effect of removal of intracellular Ca with EGTA. NCX1 inactivation is significantly slower in C739A NCX1 compared with WT: 240 s after application of EGTA a significantly greater current remains in cells expressing C739A NCX1 (right). *P < 0.05 vs. WT. B) Effect of PIP2 depletion by a large Ca transient in the absence of intracellular ATP. In this protocol, the magnitude of the initial NCX1 current remains stable for periods of many minutes although the cytoplasmic ATP concentration is nominally zero. The initial activation cycle results in complete NCX1 inactivation in WT but not C739A-expressing cells (right). **P < 0.01 vs. WT.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4608915&req=5

Figure 5: Effect of palmitoylation on NCX1 inactivation by Ca depletion and excess. Stably transfected FT-293 cells expressing WT and C739A NCX1 were voltage clamped in the whole-cell mode. Current traces are shown in red, capacitance traces in blue, and changes in extracellular Ca indicated in green. Outward NCX1 currents were activated by stepping extracellular Ca from 0 to 4 mM in cells expressing WT (left) and C739A exchangers (center). A) Effect of removal of intracellular Ca with EGTA. NCX1 inactivation is significantly slower in C739A NCX1 compared with WT: 240 s after application of EGTA a significantly greater current remains in cells expressing C739A NCX1 (right). *P < 0.05 vs. WT. B) Effect of PIP2 depletion by a large Ca transient in the absence of intracellular ATP. In this protocol, the magnitude of the initial NCX1 current remains stable for periods of many minutes although the cytoplasmic ATP concentration is nominally zero. The initial activation cycle results in complete NCX1 inactivation in WT but not C739A-expressing cells (right). **P < 0.01 vs. WT.

Mentions: Compositions of solutions in electrophysiology experiments


Palmitoylation of the Na/Ca exchanger cytoplasmic loop controls its inactivation and internalization during stress signaling.

Reilly L, Howie J, Wypijewski K, Ashford ML, Hilgemann DW, Fuller W - FASEB J. (2015)

Effect of palmitoylation on NCX1 inactivation by Ca depletion and excess. Stably transfected FT-293 cells expressing WT and C739A NCX1 were voltage clamped in the whole-cell mode. Current traces are shown in red, capacitance traces in blue, and changes in extracellular Ca indicated in green. Outward NCX1 currents were activated by stepping extracellular Ca from 0 to 4 mM in cells expressing WT (left) and C739A exchangers (center). A) Effect of removal of intracellular Ca with EGTA. NCX1 inactivation is significantly slower in C739A NCX1 compared with WT: 240 s after application of EGTA a significantly greater current remains in cells expressing C739A NCX1 (right). *P < 0.05 vs. WT. B) Effect of PIP2 depletion by a large Ca transient in the absence of intracellular ATP. In this protocol, the magnitude of the initial NCX1 current remains stable for periods of many minutes although the cytoplasmic ATP concentration is nominally zero. The initial activation cycle results in complete NCX1 inactivation in WT but not C739A-expressing cells (right). **P < 0.01 vs. WT.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4608915&req=5

Figure 5: Effect of palmitoylation on NCX1 inactivation by Ca depletion and excess. Stably transfected FT-293 cells expressing WT and C739A NCX1 were voltage clamped in the whole-cell mode. Current traces are shown in red, capacitance traces in blue, and changes in extracellular Ca indicated in green. Outward NCX1 currents were activated by stepping extracellular Ca from 0 to 4 mM in cells expressing WT (left) and C739A exchangers (center). A) Effect of removal of intracellular Ca with EGTA. NCX1 inactivation is significantly slower in C739A NCX1 compared with WT: 240 s after application of EGTA a significantly greater current remains in cells expressing C739A NCX1 (right). *P < 0.05 vs. WT. B) Effect of PIP2 depletion by a large Ca transient in the absence of intracellular ATP. In this protocol, the magnitude of the initial NCX1 current remains stable for periods of many minutes although the cytoplasmic ATP concentration is nominally zero. The initial activation cycle results in complete NCX1 inactivation in WT but not C739A-expressing cells (right). **P < 0.01 vs. WT.
Mentions: Compositions of solutions in electrophysiology experiments

Bottom Line: Surprisingly, palmitoylation does not influence trafficking or localization of NCX1 to surface membranes, nor does it strongly affect the normal forward or reverse transport modes of NCX1.However, exchangers that cannot be palmitoylated do not inactivate normally (leading to substantial activity in conditions when wild-type exchangers are inactive) and do not promote cargo-dependent endocytosis that internalizes 50% of the cell surface following strong G-protein activation or large Ca transients.The palmitoylated cysteine in NCX1 is found in all vertebrate and some invertebrate NCX homologs.

View Article: PubMed Central - PubMed

Affiliation: *Division of Cardiovascular and Diabetes Medicine, Medical Research Institute, College of Medicine, Dentistry, and Nursing, University of Dundee, Dundee, United Kingdom; and Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

No MeSH data available.


Related in: MedlinePlus