Linked Life Data

17635919

Source:http://linkedlifedata.com/resource/pubmed/id/17635919

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
36
pubmed:dateCreated
2007-9-3
pubmed:abstractText
Recruitment of RAF kinases to the plasma membrane was initially proposed to be mediated by Ras proteins via interaction with the RAF Ras binding domain (RBD). Data reporting that RAF kinases possess high affinities for particular membrane lipids support a new model in which Ras-RAF interactions may be spatially restricted to the plane of the membrane. Although the coupling features of Ras binding to the isolated RAF RBD were investigated in great detail, little is known about the interactions of the processed Ras with the functional and full-length RAF kinases. Here we present a quantitative analysis of the binding properties of farnesylated and nonfarnesylated H-Ras to both full-length B- and C-RAF in the presence and absence of lipid environment. Although isolated RBD fragments associate with high affinity to both farnesylated and nonfarnesylated H-Ras, the full-length RAF kinases revealed fundamental differences with respect to Ras binding. In contrast to C-RAF that requires farnesylated H-Ras, cytosolic B-RAF associates effectively and with significantly higher affinity with both farnesylated and nonfarnesylated H-Ras. To investigate the potential farnesyl binding site(s) we prepared several N-terminal fragments of C-RAF and found that in the presence of cysteine-rich domain only the farnesylated form of H-Ras binds with high association rates. The extreme N terminus of B-RAF turned out to be responsible for the facilitation of lipid independent Ras binding to B-RAF, since truncation of this region resulted in a protein that changed its kinase properties and resembles C-RAF. In vivo studies using PC12 and COS7 cells support in vitro results. Co-localization measurements using labeled Ras and RAF documented essential differences between B- and C-RAF with respect to association with Ras. Taken together, these data suggest that the activation of B-RAF, in contrast to C-RAF, may take place both at the plasma membrane and in the cytosolic environment.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
7
pubmed:volume
282
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
26503-16
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
B- and C-RAF display essential differences in their binding to Ras: the isotype-specific N terminus of B-RAF facilitates Ras binding.
pubmed:affiliation
Institut für Medizinische Strahlenkunde und Zellforschung, University of Wuerzburg, 97078 Wuerzburg, Germany.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't