TGF-β receptor-binding proteins:: Complex interactions

Members of the Smad protein family are fundamental downstream mediators of TGF-beta signals. However, the basic, linear Smad signaling pathway is unlikely to be the sole contributor to the plethora of cell type-specific TGF-beta responses. Investigators have identified a number of molecules that interact with the TGF-beta receptors (T beta Rs) and may explain, at least in part, the tight regulation of TGF-beta effects. Understanding these T R-interacting molecules is thus a matter of great potential significance for elucidating TGF-beta-family signal transduction. The present article reviews our current understanding of the roles and mechanisms of action of this relatively understudied group of molecules. (c) 2006 Elsevier Inc. All rights reserved.