Embryonic Patterning of Xenopus Mesoderm by Bmp-4
ext racell ular
cytoplasm
ri::
a.
~
ID
•
1- • • "
!I- _ ..
(smad-1 .-S)
( Smad-4 )
E--t "--c:_~
181
Fig_ 5_ The bone morphogenetic protein (BMP) signal transduction pathway
and synexpression group. Members of the BMP growth factors bind to and activate type I and type II receptor serine/threonine kinases leading to phosphorylation and activation of BMP receptor-specific Smad-l and -5. Upon phosphorylation Smad-l and -5 bind to a co-Smad (Smad-4) and enter the nucleus
where they associate with yet unknown transcription factors and activate transcription of target genes such as Xvent-2. Inhibitory Smad-6 and -7 interfere
with signal transduction and limit BMP signalling. Components of the BMP
pathway which are coexpressed with, and probably coregulated by, Bmp-4 are
highlighted in gray. This group of coregulated genes is called the Bmp-4 synexpression group. Non-highlighted components are mostly ubiquitously expressed
phenomenon of coordinated expression of interacting genes in a largescale screen for three other groups of genes which we refer to collectively as synexpression groups (Gawantka et aI., 1998). In the case of the
Bmp-4 synexpression group, coordinated expression may be important
for autoregulation of the pathway.
ext racell ular
cytoplasm
ri::
a.
~
ID
•
1- • • "
!I- _ ..
(smad-1 .-S)
( Smad-4 )
E--t "--c:_~
181
Fig_ 5_ The bone morphogenetic protein (BMP) signal transduction pathway
and synexpression group. Members of the BMP growth factors bind to and activate type I and type II receptor serine/threonine kinases leading to phosphorylation and activation of BMP receptor-specific Smad-l and -5. Upon phosphorylation Smad-l and -5 bind to a co-Smad (Smad-4) and enter the nucleus
where they associate with yet unknown transcription factors and activate transcription of target genes such as Xvent-2. Inhibitory Smad-6 and -7 interfere
with signal transduction and limit BMP signalling. Components of the BMP
pathway which are coexpressed with, and probably coregulated by, Bmp-4 are
highlighted in gray. This group of coregulated genes is called the Bmp-4 synexpression group. Non-highlighted components are mostly ubiquitously expressed
phenomenon of coordinated expression of interacting genes in a largescale screen for three other groups of genes which we refer to collectively as synexpression groups (Gawantka et aI., 1998). In the case of the
Bmp-4 synexpression group, coordinated expression may be important
for autoregulation of the pathway.