Linked Life Data

2295003

Source:http://linkedlifedata.com/resource/pubmed/id/2295003

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1990-2-22
pubmed:abstractText
Investigations of protein kinase C (PKC) activity have focussed on protein phosphorylation using adenosine triphosphate (ATP), not guanosine triphosphate (GTP), as the phosphate donor. In a continuing study of the enzymology of the PKC of human neutrophils, we wanted to determine if there might be protein kinases that do use GTP as a phosphate donor. Soluble extracts or detergent-extracted fractions of human neutrophils were used as enzyme sources. Phosphorylation of histone using [gamma-32P]-GTP was 31% as effective as [gamma-32P]-ATP. Phosphorylation with GTP depended on Ca2+, Mg2+, and phospholipid, just as the ATP, and the Ca2+ requirements were similar. In all cases, H-7, an inhibitor of ATP-supported PKC activity, blocked GTP-utilizing activity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed that similar endogenous proteins were phosphorylated with ATP or GTP. The apparent Km and Vmax for the enzyme(s) for both phosphate donors were identical, although these were modified by treatment with Triton X-100. GTP competitively inhibited use of ATP by PKC; however, low concentrations of ATP enhanced GTP-utilizing kinase activity in some cases. Non-hydrolyzable forms of ATP and other nucleotide triphosphates were inhibitory. Detergent treatment also markedly altered the number of proteins phosphorylated by either nucleotide. The major protein phosphorylated in the soluble or detergent extract was a single polypeptide band in the 34 Kd range. These studies are the first to explicitly examine the possible phosphorylation by neutrophil PKC using GTP and point to a potential alternative mode of enzyme activity. Since high concentrations of GTP are available within neutrophils, the ability of PKC or a PKC-like enzyme to use this nucleotide may have important ramifications in signal transduction.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0006-4971
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
75
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
479-87
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1990
pubmed:articleTitle
Human neutrophils contain a protein kinase C-like enzyme that utilizes guanosine triphosphate as a phosphate donor. Cofactor requirements, kinetics, and endogenous acceptor proteins.
pubmed:affiliation
Department of Pediatric Hematology/Oncology, University of Michigan, Ann Arbor 48109.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.