Cardiac excitation–contraction coupling is initiated with the influx of Ca2+ ions across the plasma membrane through voltage-gated L-type calcium channels. This process is tightly regulated by modulation of the channel open probability and channel localization. Protein kinase A (PKA) is found in close association with the channel and is one of the main regulators of its function. Whether this kinase is modulating the channel open probability by phosphorylation of key residues or via alternative mechanisms is unclear. This review summarizes recent findings regarding the PKA-mediated channel modulation and will highlight recently discovered regulatory mechanisms that are independent of PKA activity and involve protein–protein interactions and channel localization.
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Cover Image
Cover Image
The cover image depicts a combination of a 3D reconstruction of ER-TGN contact sites by focus ion beam-scanning electron microscopy (FIB-SEM) and five images showing the visualization of the contacts by FRET/FLIM. The 3D reconstruction of the Golgi stack was generated from FIB-SEM tomography of a HepG2 cell using IMOD software. The ER cisterna is shown in red (with ribosomes as white circles), while the trans-most cisterna of the Golgi stack is shown in green (with emerging clathrin-coated buds decorated by pink dots). The five FLIM images are from HeLa cells expressing a TGN reporter (TGN46-GFP) and an ER reporter (mCherry-Cb5). The pseudocolour scale represents donor (i.e. GFP) lifetime (τ) values ranging from 1.8 (blue) to 2.7 ns (red) under conditions that destabilize (left) or stabilize ER-TGN contact sites. For further information, see the review by Venditti and colleagues (pp. 187–197). Image courtesy of Maria Antonietta De Matteis.
New aspects in cardiac L-type Ca2+ channel regulation
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