Posttranslational Modifications of TGF-β Receptors.

TGF-β is a prototype of the TGF-β cytokine superfamily and exerts multiple regulatory effects on cell activities. It signals through two types of membrane-bound serine/threonine kinase receptors. Upon TGF-β binding, the type II receptor TβRII recruits the type I receptor TβRI and form a functional heterocomplex. TβRII trans-phosphorylates the GS region of TβRI, thus triggering its kinase activity. Activated TβRI proceeds to activate downstream Smad2/3. Signal intensity and duration through the availability, activity and destiny of TGF-β receptors are finely controlled by multiple posttranslational modifications such as phosphorylation, ubiquitination, and neddylation. This chapter introduces methods for examination of these modifications of TGF-β receptors.