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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 masking anionic phospholipid head groups. Stably transfected FT-293 cells expressing WT and C739A NCX1 were voltage clamped in the whole-cell mode using ATP-free, highly Ca-buffered cytoplasmic solutions (10 mM EGTA with 1 mM Ca). A) Using a cytoplasmic solution containing 20 µM heptalysine (K7) to bind head groups of anionic phospholipids, outward exchange currents were activated by stepping extracellular Ca from 0 to 4 mM in cells expressing WT (left) and C739A exchangers (right). Current magnitudes are given for peak currents and current remaining after 10 s. Residual currents are highly significantly increased in cells expressing C739A compared with WT exchangers. B) Using a cytoplasmic solution containing 0.15 mM Al3+ (in the presence of 10 mM EGTA) to bind PIP2 head groups, outward exchange currents were strongly suppressed in cells expressing WT exchangers (left) but remained robust in cells expressing C739A exchangers (right). **P < 0.01.
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Figure 6: Effect of palmitoylation on NCX1 inactivation by masking anionic phospholipid head groups. Stably transfected FT-293 cells expressing WT and C739A NCX1 were voltage clamped in the whole-cell mode using ATP-free, highly Ca-buffered cytoplasmic solutions (10 mM EGTA with 1 mM Ca). A) Using a cytoplasmic solution containing 20 µM heptalysine (K7) to bind head groups of anionic phospholipids, outward exchange currents were activated by stepping extracellular Ca from 0 to 4 mM in cells expressing WT (left) and C739A exchangers (right). Current magnitudes are given for peak currents and current remaining after 10 s. Residual currents are highly significantly increased in cells expressing C739A compared with WT exchangers. B) Using a cytoplasmic solution containing 0.15 mM Al3+ (in the presence of 10 mM EGTA) to bind PIP2 head groups, outward exchange currents were strongly suppressed in cells expressing WT exchangers (left) but remained robust in cells expressing C739A exchangers (right). **P < 0.01.

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 masking anionic phospholipid head groups. Stably transfected FT-293 cells expressing WT and C739A NCX1 were voltage clamped in the whole-cell mode using ATP-free, highly Ca-buffered cytoplasmic solutions (10 mM EGTA with 1 mM Ca). A) Using a cytoplasmic solution containing 20 µM heptalysine (K7) to bind head groups of anionic phospholipids, outward exchange currents were activated by stepping extracellular Ca from 0 to 4 mM in cells expressing WT (left) and C739A exchangers (right). Current magnitudes are given for peak currents and current remaining after 10 s. Residual currents are highly significantly increased in cells expressing C739A compared with WT exchangers. B) Using a cytoplasmic solution containing 0.15 mM Al3+ (in the presence of 10 mM EGTA) to bind PIP2 head groups, outward exchange currents were strongly suppressed in cells expressing WT exchangers (left) but remained robust in cells expressing C739A exchangers (right). **P < 0.01.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: Effect of palmitoylation on NCX1 inactivation by masking anionic phospholipid head groups. Stably transfected FT-293 cells expressing WT and C739A NCX1 were voltage clamped in the whole-cell mode using ATP-free, highly Ca-buffered cytoplasmic solutions (10 mM EGTA with 1 mM Ca). A) Using a cytoplasmic solution containing 20 µM heptalysine (K7) to bind head groups of anionic phospholipids, outward exchange currents were activated by stepping extracellular Ca from 0 to 4 mM in cells expressing WT (left) and C739A exchangers (right). Current magnitudes are given for peak currents and current remaining after 10 s. Residual currents are highly significantly increased in cells expressing C739A compared with WT exchangers. B) Using a cytoplasmic solution containing 0.15 mM Al3+ (in the presence of 10 mM EGTA) to bind PIP2 head groups, outward exchange currents were strongly suppressed in cells expressing WT exchangers (left) but remained robust in cells expressing C739A exchangers (right). **P < 0.01.
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