title: Evidence that the folate-requiring enzymes of de novo purine biosynthesis are encoded by individual mRNAs.
abstract: Isolation of the mRNAs encoding for the three folate-requiring enzymes involved in de novo purine biosynthesis followed by their in vitro translation resulted in three separate proteins electrophoretically identical with those previously isolated. The three enzymes are glycinamide ribonucleotide transformylase, 5-aminoimidazole-4-carboxamide ribonucleotide transformylase, and 5,10-methenyl-, 5,10-methylene-, and 10-formyltetrahydrofolate synthetase. Thus these enzymes do not appear to be derived from large multifunctional proteins that are then subject to proteolysis in vivo or during in vitro purification. The levels of these enzymatic activities were increased by approximately 2-fold after raising the concentration of protein in the chicken's diet. The observed response is similar to that noted for glutamine phosphoribosylpyrophosphate amidotransferase, the presumed rate-limiting enzymatic activity for this pathway. For 5-amino-imidazole-4-carboxamide ribonucleotide transformylase and the trifunctional synthetase but not glycinamide ribonucleotide transformylase the increase in enzymatic activity correlates with higher mRNA levels.
mesh_terms: D000217:Acyltransferases / Q000096:biosynthesis; D000619:Aminohydrolases / Q000096:biosynthesis; D000818:Animals; D019731:Carbon-Nitrogen Ligases; D002645:Chickens; D004044:Dietary Proteins / Q000494:pharmacology; D005492:Folic Acid / Q000378:metabolism*; D005574:Formate-Tetrahydrofolate Ligase / Q000096:biosynthesis; D019877:Hydroxymethyl and Formyl Transferases; D066298:In Vitro Techniques; D008025:Ligases / Q000096:biosynthesis; D008754:Methylenetetrahydrofolate Dehydrogenase (NADP) / Q000096:biosynthesis; D009097:Multienzyme Complexes / Q000096:biosynthesis; D051027:Phosphoribosylaminoimidazolecarboxamide Formyltransferase; D051026:Phosphoribosylglycinamide Formyltransferase; D011687:Purines / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000378:metabolism*
chemical_list: D004044:Dietary Proteins; D009097:Multienzyme Complexes; D011687:Purines; D012333:RNA, Messenger; C021836:formyl-methenyl-methylenetetrahydrofolate synthetase; D005492:Folic Acid; D008754:Methylenetetrahydrofolate Dehydrogenase (NADP); D019877:Hydroxymethyl and Formyl Transferases; D051026:Phosphoribosylglycinamide Formyltransferase; D051027:Phosphoribosylaminoimidazolecarboxamide Formyltransferase; D000217:Acyltransferases; D000619:Aminohydrolases; D008025:Ligases; D019731:Carbon-Nitrogen Ligases; C021557:5,10-methenyltetrahydrofolate synthetase; D005574:Formate-Tetrahydrofolate Ligase