IndraLab

"Modified assertion"

"Phosphorylation of the C-terminal serine residues in R-Smads by type I receptor kinases is a crucial step in TGF-b family signalling (Abdollah et al., 1997; Macias-Silva et al., 1996; Souchelnytskyi et al., 1997). The two most C-terminal serine residues become phosphorylated and, together with a third, non-phosphorylated serine residue, form an evolutionarily conserved SSXS motif in all R-Smads.... TGF-b and activin receptors phosphorylate Smad2 and Smad3, and BMP receptors phosphorylate Smad1, Smad5 and Smad8 (Chen et al., 1998) (Fig. 1). The consequence of R-Smad phosphorylation is the formation of oligomeric complexes with the Co-Smad, Smad4."

"Immediate early target genes of TGFbeta-Smad signalling include the inhibitory Smads, such as Smad7, which accumulate upon signalling and negatively regulate the pathway at the level of TbetaRI degradation, Smad2 and Smad3 phosphorylation by TbetaRI and at the level of chromatin bound Smad complexes, which are transcriptionally blocked by Smad7."