Abstract
Na+/Ca2+ exchanger (NCX) is one of the major mechanisms for removing Ca2+ from the cytosol especially in cardiac myocytes and neurons, where their physiological activities are triggered by an influx of Ca2+. NCX contains a large intracellular loop (NCXIL) that is responsible for regulating NCX activity. Recent evidence has shown that proteins, including kinases and phosphatases, associate with NCX1IL to form a NCX1 macro-molecular complex. To search for the molecules that interact with NCX1IL and regulate NCX1 activity, we used the yeast two-hybrid method to screen a human heart cDNA library and found that the C-terminal region of sarcomeric mitochondrial creatine kinase (sMiCK) interacted with NCX1IL. Moreover, both sMiCK and the muscle-type creatine kinase (CKM) coimmuno-precipitated with NCX1 using lysates of cardiacmyocytes and HEK293T cells that transiently expressed NCX1 and various creatine kinases. Both sMiCK and CKM were able to produce a recovery in the decreased NCX1 activity that was lost under energy-compromised conditions. This regulation is mediated through a putative PKC phosphorylation site of sMiCK and CKM. The autophosphorylation and the catalytic activity of sMiCK and CKM are not required for their regulation of NCX1 activity. Our results suggest a novel mechanism for the regulation of NCX1 activity.
Original language | English |
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Pages (from-to) | 28275-28285 |
Number of pages | 11 |
Journal | Journal of Biological Chemistry |
Volume | 285 |
Issue number | 36 |
DOIs | |
Publication status | Published - 3 Sept 2010 |