Linked Life Data

2735931

Source:http://linkedlifedata.com/resource/pubmed/id/2735931

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
11
pubmed:dateCreated
1989-7-20
pubmed:abstractText
Protein kinase C (PKC) is a Ca2+- and phospholipid-dependent protein kinase which has been implicated as a key enzyme in the regulation of cellular growth. The naphthalenesulfonamide W7 [N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide] is representative of a number of cationic amphiphilic inhibitors of PKC which appear to inhibit PKC by interacting with the acidic phospholipid cofactor of the enzyme, according to kinetic studies. In a previous report, we demonstrated that PKC binds directly to W7 when the naphthalenesulfonamide is immobilized on agarose. In the present report, we have defined the mechanism of the binding of PKC to W7-agarose, and its relevance to the inhibitory mechanism of the naphthalenesulfonamide. We demonstrate that PKC bound W7-agarose through the catalytic domain of the enzyme. An active catalytic fragment of PKC was generated by limited proteolysis, and we found that this fragment bound W7-agarose and coeluted with intact PKC upon the addition of Triton X-100. W7 inhibited PKC activity by two different mechanisms. As previously reported, W7 inhibited PKC by interacting with the phospholipid cofactor of the enzyme (IC50 = 260 microM). However, at higher concentrations of W7, we found that this naphthalenesulfonamide inhibited PKC by serving as a competitive inhibitor with respect to the substrate ATP, according to a kinetic analysis of the inhibition of the active catalytic fragment of PKC by W7. W7 inhibited the active catalytic fragment of PKC as well as PKC-catalyzed phosphorylation of protamine sulfate, a reaction which is independent of Ca2+ and phospholipid, with similar potencies. Consistent with the kinetic evidence that W7 serves as a competitive inhibitor of PKC with respect to ATP, we found that, in the presence of 10 mM MgCl2, 1 mM ATP was sufficient to elute PKC from W7-agarose. Thus, naphthalenesulfonamide PKC inhibitors may include both agents which primarily function by interacting with the phospholipid cofactor of the enzyme and agents which primarily serve as active site inhibitors of PKC.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0006-2952
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
38
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1737-42
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Binding of protein kinase C to N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide through its ATP binding site.
pubmed:affiliation
Department of Cell Biology, University of Texas M.D. Anderson Cancer Center, Houston 77030.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't