Dethiophosphorylation of thiophosphorylase [formula omitted] by a multifunctional phosphoprotein phosphatase of Mr=35,000

• Published in: Biochemical and biophysical research communications Vol. 95; no. 3; pp. 1192 - 1199
• Main Authors: Tabarini, Diane, Li, Heng-Chun
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 14.08.1980
• Subjects: Adenosine Triphosphate - analogs & derivatives; Adenosine Triphosphate - metabolism; Animals; Cations, Divalent; Cattle; Kinetics; Liver - enzymology; Manganese - pharmacology; Molecular Weight; Muscles - enzymology; Myocardium - enzymology; Phosphoprotein Phosphatases - metabolism; Phosphorylase a - metabolism; Phosphorylases - metabolism; Phosphorylation; Rabbits; Thionucleotides - metabolism
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/0006-291X(80)91599-5

It is generally believed that proteins thiophosphorylated by adenosine 5′-0-(3-thiotriphosphate) (ATPγS) are resistant to phosphoprotein phosphatases. We have found that a general phosphoprotein phosphatase of Mr=35,000 purified from bovine heart, rabbit muscle or liver, can efficiently catalyze the dethiophosphorylation of [ 35S ]thiophosphorylated phosphorylase ([ 35S ]thiophosphorylase a) . The rate of the dethiophosphorylation reaction in the presence of lmM Mn 2+ was about one-third as that of dephosphorylation of [ 32P ]phosphorylase a . The dethiophosphorylation reaction was almost completely inhibited by EDTA and was stimulated several fold by Mn 2+. On the other hand, the dephosphorylation of [ 32P ]phosphorylase a was not significantly affected by these reagents. The present findings indicate that thiophosphorylated proteins in general may not be resistant to phosphoprotein phosphatases.