Linked Life Data

2161679

Source:http://linkedlifedata.com/resource/pubmed/id/2161679

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
18
pubmed:dateCreated
1990-7-16
pubmed:abstractText
Protein kinase C (PKC) consists of a family of Ca2(+)- and phospholipid-dependent protein kinases that catalyze the transfer of the gamma-phosphate of ATP to phosphoacceptor serine or threonine residues of protein and peptide substrates. In this report, we demonstrate that purified, autophosphorylated rat brain PKC catalyzes a Ca2(+)- and phospholipid-dependent ATPase reaction, that appears to represent the bond-breaking step of its phosphotransferase reaction. The histone kinase and ATPase activities of PKC each had a Kmapp of 6 microM for ATP, and their metal ion cofactor requirements were similar. The rate of the Ca2(+)- and phospholipid-dependent PKC-catalyzed ATPase reaction was approximately 5 times slower than the rate of histone phosphorylation, but the basal rates of the PKC-catalyzed ATPase and histone kinase activities differed by less than a factor of 2. The mechanism of the ATPase reaction could entail either direct hydrolysis of ATP by water or formation of a stable phosphoenzyme (PKC-P) followed by its hydrolysis (PKC + Pi). The latter mechanism appears unlikely since [gamma-32P]ATP failed to label autophosphorylated PKC. Furthermore, the PKC preparation did not contain contaminating protein phosphatases, excluding the possibility that the ATPase activity represented dephosphorylation of contaminating PKC substrates. Therefore, our results suggest that water may effectively compete with protein substrates of PKC for the gamma-phosphate of ATP. Using PKC inhibitors and activators, we found that the ATPase and protein kinase activities of PKC were regulated analogously, providing evidence that allosteric activation of PKC involves facilitation of the bond-breaking step of the phosphotransferase reaction.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
8
pubmed:volume
29
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4278-82
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1990
pubmed:articleTitle
Characterization of a Ca2(+)- and phospholipid-dependent ATPase reaction catalyzed by rat brain protein kinase C.
pubmed:affiliation
Department of Cell Biology, University of Texas M. D. Anderson Cancer Center, Houston 77030.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't