Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.21 (CPT)
 4,580 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Carnitine status in humans is reported to vary according to body composition, gender, and diet. Plasma carnitine concentration positively correlates with the dietary intake of carnitine. The content of carnitine in foodstuff is based on old and inadequate methodology. Nevertheless, dietary carnitine is important. The molecular biology of the enzymes of carnitine biosynthesis has recently been accomplished. Carnitine biosynthesis requires pathways in different tissues and is an efficient system. Overall biosynthesis is determined by the availability of trimethyllysine from tissue proteins. Carnitine deficiency resulting from a defect in biosynthesis has yet to be reported. The role of carnitine in long-chain fatty acid oxidation is well defined. Recent evidence supports a role for the voltage-dependent anion channel in the transport of acyl-CoAs through the mitochondrial outer membrane. The mitochondrial outer membrane carnitine palmitoyltransferase-I in liver can be phosphorylated and when phosphorylated the sensitivity to malonyl-CoA is greatly decreased. This may explain the change in sensitivity of liver carnitine palmitoyltransferase-I observed during fasting and diabetes. Recently reported data clarify the role of carnitine and the carnitine transport system in the interplay between peroxisomes and mitochondrial fatty acid oxidation. Lastly, the buffering of the acyl-CoA/CoA coupled by carnitine reflects intracellular metabolism. This mass action effect underlies the use of carnitine as a therapeutic agent. In summary, these new observations help to further our understanding of the molecular aspects of carnitine in medicine.
 ...
PMID:Carnitine: a nutritional, biosynthetic, and functional perspective. 1536 36

Membrane proteins play an important role in cellular function. However, their analysis by mass spectrometry often is hindered by their hydrophobicity and/or low abundance. In this article, we present a method for the mass spectrometric analysis of membrane proteins based on the isolation of the resident membranes, isolation of the proteins by gel electrophoresis, and electroelution followed by enzymatic digestion by both trypsin and proteinase K. With this method, we have achieved 82-99% sequence coverage for the membrane proteins carnitine palmitoyltransferase-I (CPT-I), long-chain acyl-CoA synthetase (LCAS), and voltage-dependent anion channel (VDAC), isolated from rat liver mitochondrial outer membranes, including the transmembrane domains of these integral membrane proteins. This high sequence coverage allowed the identification of the isoforms of the proteins under study. This methodology provides a targeted approach for examining membrane proteins in detail.
 ...
PMID:A targeted proteomic approach for the analysis of rat liver mitochondrial outer membrane proteins with extensive sequence coverage. 1687 2

The identification of post-translational modifications is difficult especially for hydrophobic membrane proteins. Here we present the identification of several types of protein modifications on membrane proteins isolated from mitochondrial outer membranes. We show, in vivo, that the mature rat liver mitochondrial carnitine palmitoyltransferase-I enzyme is N-terminally acetylated, phosphorylated on two threonine residues, and nitrated on two tyrosine residues. We show that long chain acyl-CoA synthetase 1 is acetylated at both the N-terminal end and at a lysine residue and tyrosine residues are found to be phosphorylated and nitrated. For the three voltage-dependent anion channel isoforms present in the mitochondria, the N-terminal regions of the protein were determined and sites of phosphorylation were identified. These novel findings raise questions about regulatory aspects of carnitine palmitoyltransferase-I, long chain acyl-CoA synthetase and voltage dependent anion channel and further studies should advance our understanding about regulation of mitochondrial fatty acid oxidation in general and these three proteins in specific.
 ...
PMID:Post-translational modifications of rat liver mitochondrial outer membrane proteins identified by mass spectrometry. 1747 30

CPT1a (carnitine palmitoyltransferase 1a) in the liver mitochondrial outer membrane (MOM) catalyzes the primary regulated step in overall mitochondrial fatty acid oxidation. It has been suggested that the fundamental unit of CPT1a exists as a trimer, which, under native conditions, could form a dimer of the trimers, creating a hexamer channel for acylcarnitine translocation. To examine the state of CPT1a in the MOM, we employed a combined approach of sizing by mass and isolation using an immunological method. Blue native electrophoresis followed by detection with immunoblotting and mass spectrometry identified large molecular mass complexes that contained not only CPT1a but also long chain acyl-CoA synthetase (ACSL) and the voltage-dependent anion channel (VDAC). Immunoprecipitation with antisera against the proteins revealed a strong interaction between the three proteins. Immobilized CPT1a-specific antibodies immunocaptured not only CPT1a but also ACSL and VDAC, further strengthening findings with blue native electrophoresis and immunoprecipitation. This study shows strong protein-protein interaction between CPT1a, ACSL, and VDAC. We propose that this complex transfers activated fatty acids through the MOM.
 ...
PMID:Mitochondrial carnitine palmitoyltransferase 1a (CPT1a) is part of an outer membrane fatty acid transfer complex. 2162 68

By interrogating metabolic programs in the peripheral blood mononuclear cells (PBMC) of acutely infected COVID-19 patients, we identified novel and distinct immune cell subsets Our studies identified a non-clonal population of T cells expressing high H3K27me3 and voltage-dependent anion channel (VDAC) with mitochondrial dysfunction and increased susceptibility to cell death. Characterized by dysmorphic mitochondria and increased cytoplasmic cytochrome c, apoptosis of these cells was inhibited by preventing VDAC aggregation or blocking caspase activation. Further, we observed a marked increase in Hexokinase II+ polymorphonuclear-myeloid derived suppressor cells (PMN-MDSC). While PMN-MDSC were also found in the PBMC of patients with other viral infections, the Hexokinase II+ PMN-MDSC were found exclusively in the acute COVID-19 patients with moderate or severe disease. Finally, we identified a population of monocytic MDSC (M-MDSC) expressing high carnitine palmitoyltransferase I (CPT1a) and VDAC, which were present in the PBMC of the acute COVID-19 patients, but not recovered COVID-19 patients and whose presence correlated with severity of disease. Overall, these unique populations of immune cells provide insight into the pathogenesis of SARS-CoV-2 infection and provide a means to predict and track disease severity as well as an opportunity to design and evaluate novel therapeutic regimens.
 ...
PMID:Mitochondrial induced T cell apoptosis and aberrant myeloid metabolic programs define distinct immune cell subsets during acute and recovered SARS-CoV-2 infection. 3293 20