High impact information on CPT1

• In this study we report that CPT1- and EPT1-derived cholinephosphotransferase activities can significantly overlap in vivo such that EPT1 can contribute to 60% of net phosphatidylcholine synthesis via the Kennedy pathway [1].
• In yeast, diacylglycerol accepts a phosphocholine moiety through a CPT1-derived cholinephosphotransferase activity to directly synthesize phosphatidylcholine [1].
• Functional analysis of the deleted CPT1 proteins indicates that this folded C-terminal core, which may belong to the catalytic domain of CPT1, requires TM2 for its correct folding achievement and is in close proximity to residues 1-47 [2].
• We have previously shown that the first 147 N-terminal residues of the rat liver carnitine palmitoyltransferase 1 (CPT1), encompassing its two transmembrane (TM) segments, specify both mitochondrial targeting and anchorage at the outer mitochondrial membrane (OMM) [2].
• Inositol-dependent reductions in CPT1 derived choline-phosphotransferase activity correlated with transcript levels in both wild type and ept- backgrounds [3].

Biological context of CPT1

• The complete nucleotide sequence of the Saccharomyces cerevisiae CPT1 gene, a structural gene for the sn-1,2-diacylglycerol cholinephosphotransferase (Hjelmstad, R. H., and Bell, R. M. (1987) J. Biol. Chem. 262, 3909-3917), was determined [4].
• The previously constructed cpt1::LEU2 insertional mutation was shown to involve disruption of the CPT1 open reading frame approximately in the middle; this construct did not support the production of a stable transcript [4].
• Comparative analysis of this set of protein homologies and the related set of protein homologies to the CPT1 gene product permitted identification of a presumptive active site region which contains highly conserved and divergent subregions and a common mononucleotide binding site [5].
• The CPT1 promoter region contained several elements homologous to the promoter regions of other phospholipid biosynthetic structural genes [4].
• The inferred 44,525-dalton EPT1 gene product exhibited 54% amino acid sequence homology to the cholinephosphotransferase product of the yeast CPT1 gene [5].

Anatomical context of CPT1

• The activities of the CPT1 and EPT1 gene products were independently studied in membranes prepared from strains mutant in the cognate locus using mixed micellar assays [6].
• Two phospholipid-synthesizing enzymes, namely phosphatidylinositol synthase and sn-1,2-diacylglycerol cholinephosphotransferase, are detected in the Golgi at a specific activity which exceeds that of the endoplasmic reticulum [7].

Associations of CPT1 with chemical compounds

• sn-1,2-diacylglycerol choline- and ethanolaminephosphotransferases in Saccharomyces cerevisiae. Mixed micellar analysis of the CPT1 and EPT1 gene products [6].
• The EPT1 gene product utilized CDP-ethanolamine, -monomethylethanolamine, -dimethylethanolamine, and -choline to significant extents, while the CPT1 gene product manifested relative specificity for CDP-choline and -dimethylethanolamine [6].
• Only chimeras expressing the CDP-aminoalcohol specificity region of CPT1 were capable of PC synthesis via the CDP-choline pathway in vivo [8].
• Using yeast mutants generated by disruption of the ethanolaminephosphotransferase (EPT1) and cholinephosphotransferase (CPT1) genes, we report data consistent with the proposal that the ethanolamine residue is derived from phosphatidylethanolamine [9].
• The data also implicate the CPT1 gene product in PC biosynthesis from an endogenous source of choline derived from turnover of PC via the phosphatidylserine-dependent route for PC synthesis [8].

Other interactions of CPT1

• Moreover, the ethanolamine effect observed for cki and cpt1 mutants was independent of the choline content of the growth medium [10].

References