SMAD7 binds to SMURF1

SMAD7 binds to SMURF1 in the nucleus (Ebisawa et al. 2001, Tajima et al. 2003). SMURF1 domains WW1 and WW2, highly similar to WW2 and WW3 domains of SMURF2, are involved in SMAD7 binding. SMURF1 has two splicing isoforms. The shorter splicing isoform of SMURF1 has an inter-WW domain linker of the same length as the WW2-WW3 domain linker of SMURF2. The longer isoform of SMURF1 has a longer WW1-WW2 domain linker, resulting in decreased affinity of the longer SMURF1 isoform for SMAD7 (Chong et al. 2010). This is based on experiments with recombinant mouse Smad7 and recombinant human SMURF1.

SMAD7与细胞核中的SMURF1结合（Ebisawa 等，2001年，Tajima 等，2003年）。SMURF1的WW1和WW2结构域，与SMURF2的WW2和WW3结构域高度相似，参与SMAD7的结合。SMURF1存在两种剪接异构体。SMURF1较短的剪接异构体具有与SMURF2的WW2-WW3结构域连接器相同长度的WW结构域连接器。SMURF1较长的异构体具有较长的WW1-WW2结构域连接器，导致较长的SMURF1异构体对SMAD7的亲和力降低（Chong 等，2010年）。此发现基于对重组小鼠Smad7和重组人SMURF1的实验研究。