PMID- 2753226
OWN - NLM
STAT- MEDLINE
DCOM- 19890831
LR  - 20190813
IS  - 0303-7207 (Print)
IS  - 0303-7207 (Linking)
VI  - 63
IP  - 1-2
DP  - 1989 May
TI  - Phosphorylation of proteins in rat ovarian plasma membranes by [gamma-32P]GTP: 
      evidence for the formation of a high energy phosphoprotein.
PG  - 175-87
AB  - Incubation of rat ovarian plasma membranes with [gamma-32P]guanosine 
      5'-triphosphate (GTP) in the presence of an adenosine triphosphate (ATP)-trapping 
      system results in the labeling of a single protein, Mr 33,000 +/- 3000 designated 
      'a' (Amir-Zaltsman, Y., Ezra, E., Walker, M., Lindner, H. R. and Salomon, Y. 
      (1980) FEBS Lett. 122, 166-170). Based on competition with other nucleotides it 
      is concluded that protein 'a' is preferentially phosphorylated by [gamma-32P]GTP 
      (Km = 0.28 microM). Phosphorylation of protein 'a' does not occur at pH less than 
      5 and progressively increases to plateau levels at pH 7-9. Phosphorylation of 
      protein 'a' is absolutely dependent on the presence of divalent cations 1 mM 
      Mg2+, Ca2+, or Cd2+. At higher concentrations, 5-20 mM, Mg2+ or in the presence 
      of 1 mM Mn2+ ions other proteins are also phosphorylated. While vanadate ions 
      selectively prevent the labeling of protein 'a', molybdate ions were found to 
      inhibit phosphorylation of all the membrane proteins including protein 'a'. In 
      contrast to molybdate ions, vanadate ions were found to accelerate the 
      dephosphorylation of phosphoprotein 'a'. We suggest that phosphoprotein 'a' is a 
      high energy protein intermediate in which the phosphate is present as a 
      phosphoramidate for the following reasons: (i) Guanosine diphosphate (GDP) but 
      not guanosine 5'-O-(2-thiodiphosphate) selectively accelerated the 
      dephosphorylation of phosphoprotein 'a' but only in the presence of Mg2+ ions. 
      (ii) The phosphoprotein intermediate is hydrolyzed in the presence of 
      hydroxylamine. (iii) Phosphoprotein 'a' is labile in the presence of 1 N HCl but 
      stable in 1 N NaOH at 37 degrees C. (iv) Phosphoprotein 'a' is heat labile. 
      Phosphoprotein 'a' is readily digested by several proteolytic enzymes and a 
      single cleavage peptide is generated upon treatment with Staphylococcus aureus V8 
      protease. The properties of protein 'a' were compared and found different from 
      another phosphoprotein Mr 90,000 +/- 1000, designated 'b' that was selected 
      arbitrarily. We propose that protein 'a' is a GTP requiring enzyme intermediate, 
      of yet unidentified function.
FAU - Amir-Zaltsman, Y
AU  - Amir-Zaltsman Y
AD  - Department of Hormone Research, Weizmann Institute of Science, Rehovot, Israel.
FAU - Salomon, Y
AU  - Salomon Y
LA  - eng
PT  - Journal Article
PL  - Ireland
TA  - Mol Cell Endocrinol
JT  - Molecular and cellular endocrinology
JID - 7500844
RN  - 0 (Hydroxylamines)
RN  - 0 (Membrane Proteins)
RN  - 0 (Nucleotides)
RN  - 0 (Phosphoproteins)
RN  - 0 (Phosphorus Radioisotopes)
RN  - 86-01-1 (Guanosine Triphosphate)
RN  - I38ZP9992A (Magnesium)
SB  - IM
MH  - Animals
MH  - Cell Membrane/analysis/metabolism
MH  - Female
MH  - Guanosine Triphosphate/analysis/*pharmacology
MH  - Hydrogen-Ion Concentration
MH  - Hydroxylamines/pharmacology
MH  - Magnesium/physiology
MH  - Membrane Proteins/analysis/*metabolism
MH  - Nucleotides/pharmacology
MH  - Ovary/cytology/metabolism/*ultrastructure
MH  - Phosphoproteins/analysis/*metabolism
MH  - Phosphorus Radioisotopes
MH  - Phosphorylation
MH  - Rats
EDAT- 1989/05/01 00:00
MHDA- 1989/05/01 00:01
CRDT- 1989/05/01 00:00
PHST- 1989/05/01 00:00 [pubmed]
PHST- 1989/05/01 00:01 [medline]
PHST- 1989/05/01 00:00 [entrez]
AID - 10.1016/0303-7207(89)90094-4 [doi]
PST - ppublish
SO  - Mol Cell Endocrinol. 1989 May;63(1-2):175-87. doi: 10.1016/0303-7207(89)90094-4.