title: Impact of phosphomimetic and non-phosphorylatable mutations of phospholemman on L-type calcium channels gating in HEK 293T cells.
abstract: BACKGROUND
  Phospholemman (PLM) is an important phosphorylation substrate for protein kinases A and C in the heart. Until now, the association between PLM phosphorylation status and L-type calcium channels (LTCCs) gating has not been fully understood. We investigated the kinetics of LTCCs in HEK 293T cells expressing phosphomimetic or nonphosphorylatable PLM mutants.
  
  
  METHODS
  The LTCCs gating was measured in HEK 293T cells transfected with LTCC and wild-type (WT) PLM, phosphomimetic or nonphosphorylatable PLM mutants: 6263AA, 6869AA, AAAA, 6263DD, 6869DD or DDDD.
  
  
  RESULTS
  WT PLM significantly slowed LTCCs activation and deactivation while enhanced voltage-dependent inactivation (VDI). PLM mutants 6869DD and DDDD significantly increased the peak of the currents. 6263DD accelerated channel activation, while 6263AA slowed it more than WT PLM. 6869DD significantly enhanced PLM-induced increase of VDI. AAAA slowed the channel activation more than 6263AA, and DDDD accelerated the channel VDI more than 6869DD.
  
  
  CONCLUSIONS
  Our results demonstrate that phosphomimetic PLM could stimulate LTCCs and alter their dynamics, while PLM nonphosphorylatable mutant produced the opposite effects.
authors: Department of Cardiology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors: Kai
authors: K
authors: Guo
authors: Yue-Peng
authors: YP
authors: Wang
authors: Zhi-Wen
authors: ZW
authors: Zhou
authors: Yi-Bo
authors: YB
authors: Jiang
authors: Wei
authors: W
authors: Li
authors: Xiao-Meng
authors: XM
authors: Chen
authors: Yi-Gang
authors: YG
authors: Li
mesh_terms: D020746:Calcium Channels, L-Type / Q000235:genetics*; D002460:Cell Line; D057809:HEK293 Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D032383:Myocytes, Cardiac / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010750:Phosphoproteins / Q000235:genetics* / Q000378:metabolism*; D010766:Phosphorylation / Q000235:genetics*
chemical_list: D020746:Calcium Channels, L-Type; D008565:Membrane Proteins; D010750:Phosphoproteins; C069141:phospholemman
keywords: L-type calcium channels; activation; deactivation; phospholemman; phosphorylation sites mutation; voltage-dependent inactivation
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