title: Developmentally regulated interconversions between end product-inhibitable and noninhibitable forms of a first pathway-specific enzyme activity can be mimicked in vitro by protein dephosphorylation-phosphorylation reactions.
abstract: During the life cycle of Blastocladiella emersonii, dramatic shifts occur in the sensitivity of the first hexosamine biosynthetic pathway-specific enzyme [amidotransferase; 2-amino-2-deoxy-D-glucose-6-phosphate ketol-isomerase (amino-transferring), EC 5.3.1.19] to end product inhibition. These shifts are developmentally correlated with changes in the utilization of the end product (uridine-5'-diphospho-N-acetylglucosamine) for chitin synthesis [Selitrennikoff, C. P., Dalley, N. E. & Sonneborn, D. R. (1980) Proc. Natl. Acad. Sci. USA 77, 5998-6002]. Alterations in amidotransferase sensitivity to end product inhibition can be mimicked by in vitro protein dephosphorylation-phosphorylation reactions, as follows: (i) Zoospore end product-inhibitable amidotransferase activity can be converted to a noninhibitable form by an endogenous (zoospore) protein phosphatase (phosphoprotein phosphohydrolase EC 3.1.3.16) reaction; this noninhibitable form can be converted back to an inhibitable form either by an endogenous cAMP-independent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) reaction or with an added cAMP-dependent protein kinase. (ii) Noninhibitable amidotransferase activity from growing cells can also be converted to the inhibitable form with added protein kinase.
mesh_terms: D001754:Blastocladiella / Q000502:physiology*; D002238:Carbohydrate Epimerases / Q000378:metabolism*; D002454:Cell Differentiation; D002474:Cell-Free System; D005246:Feedback; D005658:Fungi / Q000502:physiology*; D005786:Gene Expression Regulation; D005945:Glutamine-Fructose-6-Phosphate Transaminase (Isomerizing) / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010750:Phosphoproteins / Q000502:physiology*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D013172:Spores, Fungal / Q000502:physiology*
chemical_list: D010750:Phosphoproteins; D005945:Glutamine-Fructose-6-Phosphate Transaminase (Isomerizing); D011494:Protein Kinases; D002238:Carbohydrate Epimerases