sub:provenance {
  beldoc: dce:description "Approximately 2000 hand curated statements drawn from 57 PubMeds." ;
    dce:rights "Copyright (c) 2011-2012, Selventa. All Rights Reserved." ;
    dce:title "BEL Framework Small Corpus Document" ;
    dcterms:license "Creative Commons Attribution-Non-Commercial-ShareAlike 3.0 Unported License" ;
    pav:authoredBy sub:_6 ;
    pav:version "1.6" .
  sub:_5 prov:value """Phosphorylation.  Raf is principally activated by phosphorylation of specific amino
acid residues as shown for each isoform in Figure 4. From an evolutionary standpoint,
the Raf activation sites are highly conserved from yeast to humans. Several
amino acids in Raf, particularly serine (S) 259 and S621, which bind 14-3-3
and maintain C-Raf in a closed auto-inhibited conformation, are phosphorylated
in the basal state.137  On stimulation, Ras-GTP displaces 14-3-3 from S259, and
C-Raf is translocated to the cell membrane, where it can be dephosphorylated at
S259 by protein phosphatase 2A or other phosphatases.126  S259 also represents the
site of inhibitory phosphorylation by PKB/Akt, PKA, and serum glucocorticoid-inducible
kinase.121,138,139  Phosphorylation at S621 seems to have greater significance
because mutations at this site inactivate Raf's kinase activity. Hence,
a balance of phosphorylation and dephosphorylation is required to prime Raf in
the basal state before stimulation by Ras or mitogens.137""" ;
    prov:wasQuotedFrom pubmed:16170185 .
  sub:_6 rdfs:comment "support@belframework.org" ;
    rdfs:label "Selventa" .
  sub:assertion prov:hadPrimarySource pubmed:16170185 ;
    prov:wasDerivedFrom beldoc: , sub:_5 .
}