Abstract
Nucleoside diphosphate kinase A (NDPK-A) regulates the a1 isoform of the AMP-activated protein kinase (AMPK a1) selectively, independent of [AMP] and surrounding [ATP], by a process termed substrate channelling. Here, we show, using a range of empirically validated biochemical techniques, that the muscle form (M-LDH or LDH-A) and the heart form (H-LDH or LDH-B) of lactate dehydrogenase are physically associated with the liver cytosolic substrate-channelling complex such that M-LDH associates with NDPK-A, AMPKa1 and casein kinase 2 (CK2), whereas H-LDH associates with local NDPK-B. We find that the species of LDH bound to the substrate-channelling complex regulates the in vivo enzymatic activities of both AMPK and CK2, and has a downstream effect on the phospho-status of acetyl CoA carboxylase, a key regulator of cellular fat metabolism known to be a part of the cytosolic substrate-channelling complex in vivo. We hypothesise that the regulatory presence of LDH in the complex couples the substrate-channelling mechanism to both the glycolytic and redox states of the cell, allowing for efficient sensing of cell metabolic status, interfacing with the substrate-channelling complex and regulating the enzymatic activities of AMPK and CK2, two critical protein kinases.
Original language | English |
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Pages (from-to) | 349-61 |
Number of pages | 13 |
Journal | Journal of Molecular Biology |
Volume | 371 |
Issue number | 2 |
DOIs | |
Publication status | Published - 10 Aug 2007 |
Keywords
- Animals
- Cytosol
- Isoelectric Focusing
- L-Lactate Dehydrogenase
- Mice
- Myocardium
- Protein Binding
- Protein Isoforms
- Protein Subunits
- RNA, Small Interfering
- Rats
- Recombinant Proteins
- Substrate Specificity