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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 function. 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, changes in extracellular solution indicated in green, and changes in pipette solution in pink. A) Outward NCX1 currents in the presence of both 0.1 and 0.5 µM intracellular Ca were activated by stepping extracellular Ca from 0 to 4 mM in cells expressing WT (left) and C739A exchangers (center). No differences in outward exchanger current were observed in WT or nonpalmitoylatable NCX1 (right). B) Inward NCX1 currents in the presence of both 0.5 and 3 µM intracellular Ca were activated by the application of 120 mM extracellular Na in exchange for Li in cells expressing WT (left) and C739A exchangers (center). No differences in inward exchanger currents were observed in WT or nonpalmitoylatable NCX1 (right). Current transients that occur during the activation of inward currents by extracellular Na likely reflect cytoplasmic Ca depletion, namely because the buffer capacity of EGTA is weak when it is nearly saturated with Ca to generate 3 µM free Ca.
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Figure 4: Effect of palmitoylation on NCX1 function. 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, changes in extracellular solution indicated in green, and changes in pipette solution in pink. A) Outward NCX1 currents in the presence of both 0.1 and 0.5 µM intracellular Ca were activated by stepping extracellular Ca from 0 to 4 mM in cells expressing WT (left) and C739A exchangers (center). No differences in outward exchanger current were observed in WT or nonpalmitoylatable NCX1 (right). B) Inward NCX1 currents in the presence of both 0.5 and 3 µM intracellular Ca were activated by the application of 120 mM extracellular Na in exchange for Li in cells expressing WT (left) and C739A exchangers (center). No differences in inward exchanger currents were observed in WT or nonpalmitoylatable NCX1 (right). Current transients that occur during the activation of inward currents by extracellular Na likely reflect cytoplasmic Ca depletion, namely because the buffer capacity of EGTA is weak when it is nearly saturated with Ca to generate 3 µM free Ca.

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 function. 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, changes in extracellular solution indicated in green, and changes in pipette solution in pink. A) Outward NCX1 currents in the presence of both 0.1 and 0.5 µM intracellular Ca were activated by stepping extracellular Ca from 0 to 4 mM in cells expressing WT (left) and C739A exchangers (center). No differences in outward exchanger current were observed in WT or nonpalmitoylatable NCX1 (right). B) Inward NCX1 currents in the presence of both 0.5 and 3 µM intracellular Ca were activated by the application of 120 mM extracellular Na in exchange for Li in cells expressing WT (left) and C739A exchangers (center). No differences in inward exchanger currents were observed in WT or nonpalmitoylatable NCX1 (right). Current transients that occur during the activation of inward currents by extracellular Na likely reflect cytoplasmic Ca depletion, namely because the buffer capacity of EGTA is weak when it is nearly saturated with Ca to generate 3 µM free Ca.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: Effect of palmitoylation on NCX1 function. 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, changes in extracellular solution indicated in green, and changes in pipette solution in pink. A) Outward NCX1 currents in the presence of both 0.1 and 0.5 µM intracellular Ca were activated by stepping extracellular Ca from 0 to 4 mM in cells expressing WT (left) and C739A exchangers (center). No differences in outward exchanger current were observed in WT or nonpalmitoylatable NCX1 (right). B) Inward NCX1 currents in the presence of both 0.5 and 3 µM intracellular Ca were activated by the application of 120 mM extracellular Na in exchange for Li in cells expressing WT (left) and C739A exchangers (center). No differences in inward exchanger currents were observed in WT or nonpalmitoylatable NCX1 (right). Current transients that occur during the activation of inward currents by extracellular Na likely reflect cytoplasmic Ca depletion, namely because the buffer capacity of EGTA is weak when it is nearly saturated with Ca to generate 3 µM free Ca.
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