Linked Life Data

1536948

Source:http://linkedlifedata.com/resource/pubmed/id/1536948

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
1992-3-30
pubmed:abstractText
The unstimulated platelet surface contains a specific and saturable binding site for high molecular weight kininogen (HK) and low molecular weight kininogen (LK). Investigations were performed with purified heavy and light chains of HK to determine which portion(s) of the HK molecule binds to the platelet surface. Purified 64-Kd heavy chain of HK and 56-Kd light chain of HK, independently, inhibited 125I-HK binding to unstimulated platelets with a 50% inhibitory concentration (IC50) of 84 nmol/L (apparent Ki, 30 nmol/L) and 30 nmol/L (apparent Ki, 11 nM), respectively. The ability of each of the purified chains of HK to independently inhibit 125I-HK binding was not due to cleavage, reduction, and alkylation of the protein, because two-chain HK, produced by treating HK the same way as purifying the separate chains, inhibited binding similarly to intact HK. Further, purified LK alone inhibited 125I-HK binding to platelets (Ki, 17 +/- 1 nmol/L, n = 7). The 64-Kd heavy chain of HK was a competitive inhibitor on a reciprocal plot of 125I-HK-platelet binding with an apparent Ki of 28 +/- 6 nmol/L (n = 4). Independently, purified 56-Kd light chain of HK was also found to be a competitive inhibitor of 125I-HK-platelet binding, with an apparent Ki of 11 +/- 3 nmol/L (mean +/- SEM, n = 4). These indirect studies indicated that HK binds to platelets by two portions of the molecule, one on the heavy chain and another on the light chain. Studies with 125I-light chain of HK showed that it specifically bound directly to platelets in the presence of zinc, since it was blocked by HK, light chain of HK, or EDTA, but not by LK, C1s, C1 inhibitor, plasmin, factor XIII, or fibrinogen. Purified light chain of HK did not inhibit direct 125I-LK binding to platelets. HK was found to bind to platelets in an unmodified form. HK bound to platelets was cleaved by plasma or urinary kallikrein at a slower rate than the same concentration of soluble HK or HK bound and subsequently eluted from the platelet surface. Cleavage of platelet-bound HK correlated with bradykinin liberation. These studies indicate that HK has two domains on its molecule that bind to platelets. Further, platelet-bound HK is protected from kallikreins' proteolysis. This latter finding suggests that cell binding may modify the rate of bradykinin liberation from HK.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0006-4971
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
79
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1233-44
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
High molecular weight kininogen binds to platelets by its heavy and light chains and when bound has altered susceptibility to kallikrein cleavage.
pubmed:affiliation
Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't