High impact information on EPT1

• The deduced amino acid sequence of the soybean cDNA showed nearly equal similarity to each of the two characterized AAPTase sequences from yeast, cholinephosphotransferase and ethanolaminephosphotransferase (CDP-ethanolamine:sn-1,2-diacylglycerol ethanolaminephosphotransferase) [1].
• Cloning and molecular analysis reveal that the NDT80 gene maps on the right arm of chromosome VIII between EPT1 and a Phe-tRNA gene, encodes a 627-amino-acid protein which exhibits no significant homology to other known proteins, and is transcribed specifically during middle meiotic prophase [2].
• 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 [3].
• EPT1-derived activity can transfer either phosphocholine or phosphoethanolamine to diacylglcyerol in vitro, but is currently believed to primarily synthesize phosphatidylethanolamine in vivo [3].
• This contrasted with our previously cloned human choline/ethanolaminephosphotransferase cDNA that was demonstrated to code for a dual specificity choline/ethanolaminephosphotransferase [4].

Biological context of EPT1

• The cholinephosphotransferase activities in strains bearing the EPT1 gene on multicopy plasmids were elevated 13- to 23-fold and were CMP-sensitive [5].
• The EPT1 gene was cloned by complementation of ept1 using a yeast genomic library and was localized to a 2.1-kilobase region of DNA [5].
• The inferred 44,525-dalton EPT1 gene product exhibited 54% amino acid sequence homology to the cholinephosphotransferase product of the yeast CPT1 gene [6].
• The complete nucleotide sequence of the Saccharomyces cerevisiae EPT1 gene, a structural gene encoding an sn-1,2-diacylglycerol ethanolamine- and cholinephosphotransferase (Hjelmstad, R. H., and Bell, R. M. (1988) J. Biol. Chem. 263, 19748-19757), was determined [6].
• A haploid cpt1 ept1 double null mutant lacked detectable choline- and ethanolaminephosphotransferase activity but was viable for growth, establishing that these enzymes are nonessential [7].

Anatomical context of EPT1

• 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 [7].
• Enzymatic assays of C. reinhardtii EPT from the complemented yeast microsomes demonstrated that the C. reinhardtii EPT synthesized both PC and PE in the transformed yeast [8].

Associations of EPT1 with chemical compounds

• sn-1,2-diacylglycerol choline- and ethanolaminephosphotransferases in Saccharomyces cerevisiae. Mixed micellar analysis of the CPT1 and EPT1 gene products [7].
• 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 [7].
• Since both the CPT1 and EPT1 gene products catalyze the cholinephosphotransferase reaction in vitro (Hjelmstad, R. H., and Bell, R. M. (1991) J. Biol. Chem. 266, 4357-4365), the effect of inositol on these two separate routes for PC biosynthesis was investigated [9].
• Incorporation of 32Pi into phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine in wild type and ept1 strains was decreased in the presence of exogenous inositol [10].
• Regional protein homologies were identified between the EPT1 gene product and several enzymes as well as the nicotinic acetylcholine receptor [6].

Analytical, diagnostic and therapeutic context of EPT1

• Ethanolaminephosphotransferase has yet to be purified from any source and its cDNA has not been isolated from any mammalian source, thus preventing the generation of antibodies necessary to directly examine its intracellular location through immunofluorescence or electron microscopy approaches [11].

References