Linked Life Data

1361189

Source:http://linkedlifedata.com/resource/pubmed/id/1361189

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
36
pubmed:dateCreated
1993-1-21
pubmed:abstractText
We have investigated the role of serine 40 (Ser-40) in tyrosine hydroxylase (TH) catalysis of basal and activated enzymes by protein kinase A (PKA)-mediated phosphorylation. Wild type and mutant TH were transiently and stably expressed in AtT-20 cells, and the enzymatic activities of the recombinant enzymes were analyzed. The specific enzymatic activity of transiently expressed TH mutants Ser-40-->leucine or-->tyrosine (Leu-40m or Tyr-40m) was higher than that of the wild type enzyme or of other mutants in which Ser-8, -19, and -31 were replaced by leucine. The kinetic studies carried out with the stably expressed TH show that the Km for the cofactor 6-methyltetrahydropterine is lower and the Ki for dopamine is higher when the enzymatic hydroxylation is catalyzed by the Leu-40m or Tyr-40m than by the wild type enzyme. The kinetic parameters and the pH profile of the enzymatic hydroxylation catalyzed by the Leu-40m or Tyr-40m are similar to the enzyme activated by PKA-mediated phosphorylation. We suggest that Ser-40 in TH exerts an inhibitory influence on the enzymatic activity, and its replacement with another amino acid by site-directed mutagenesis or its modification by phosphorylation leads to a change in conformation with an increased enzymatic activity. The importance of Ser-40 in the activation of TH by PKA-mediated phosphorylation was investigated by comparing the activation of the wild type enzyme with that of Leu-40m or Tyr-40m. The findings that the enzymatic activity is increased by PKA-mediated phosphorylation of the wild type enzyme, but not of the Leu-40m or Tyr-40m, demonstrate that phosphorylation at Ser-40 is essential for activation of TH by PKA. The findings that addition of ATP plus cAMP to homogenates from transfected AtT-20 cells stimulates the recombinant wild type TH activity indicate that these cells contain endogenous cAMP-dependent protein kinase.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
267
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
25754-8
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed-meshheading:1361189-Amino Acid Sequence, pubmed-meshheading:1361189-Animals, pubmed-meshheading:1361189-Base Sequence, pubmed-meshheading:1361189-Blotting, Western, pubmed-meshheading:1361189-Catalysis, pubmed-meshheading:1361189-DNA, pubmed-meshheading:1361189-Enzyme Activation, pubmed-meshheading:1361189-Gene Library, pubmed-meshheading:1361189-Kinetics, pubmed-meshheading:1361189-Molecular Sequence Data, pubmed-meshheading:1361189-Mutagenesis, Site-Directed, pubmed-meshheading:1361189-Oligodeoxyribonucleotides, pubmed-meshheading:1361189-PC12 Cells, pubmed-meshheading:1361189-Polymerase Chain Reaction, pubmed-meshheading:1361189-Protein Kinases, pubmed-meshheading:1361189-Rats, pubmed-meshheading:1361189-Recombinant Proteins, pubmed-meshheading:1361189-Serine, pubmed-meshheading:1361189-Transfection, pubmed-meshheading:1361189-Tumor Cells, Cultured, pubmed-meshheading:1361189-Tyrosine 3-Monooxygenase
pubmed:year
1992
pubmed:articleTitle
Site-directed mutagenesis of tyrosine hydroxylase. Role of serine 40 in catalysis.
pubmed:affiliation
New York University Medical Center, Department of Psychiatry, Millhauser Laboratories, New York.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.