R-SMAD

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R-SMADs are receptor-regulated

TGF-β superfamily ligand signaling from cell membrane bound TGF-β receptors into the nucleus where they activate transcription TGF-β target genes. R-SMADS are directly phosphorylated on their c-terminus by type 1 TGF-β receptors through their intracellular kinase domain, leading to R-SMAD activation.[1]

R-SMADS include SMAD2 and SMAD3 from the TGF-β/Activin/Nodal branch, and SMAD1, SMAD5 and SMAD8 from the BMP/GDP branch of TGF-β signaling.[1]

In response to signals by the

phosphorylated at an SSXS motif at their extreme C-terminus. These proteins then typically bind to the common mediator Smad or co-SMAD SMAD4
.

Smad complexes then accumulate in the cell nucleus where they regulate transcription of specific target genes:

  • SMAD2 and SMAD3 are activated in response to
    Activin
    or Nodal signals.
  • SMAD1, SMAD5 and SMAD8 (also known as SMAD9) are activated in response to BMPs bone morphogenetic protein or GDP signals.

SMAD6 and SMAD7 may be referred to as I-SMADs (inhibitory SMADS), which form trimers with R-SMADS and block their ability to induce gene transcription by competing with R-SMADs for receptor binding and by marking TGF-β receptors for degradation.

See also

References

  1. ^
    PMID 19855012
    .

Further reading

External links

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