The signal transducer gp130: Solution structure of the carboxy-terminal domain of the cytokine receptor homology region

The transmembrane glycoprotein gp130 is the common signal transducing recep tor subunit of the interleukin-6-type cytokines. It is a member of the cyto kine-receptor superfamily predicted to consist of six domains in its extrac ellular part. The second and third domain constitute the cytokine-binding m odule defined by a set of four conserved cysteines and a WSXWS motif, respe ctively. The three-dimensional structure of the carboxy-terminal domain of this region was determined by multidimensional NMR. The domain consists of seven beta-strands constituting a fibronectin type III-like topology. The s tructure reveals that the WSDWS motif of gp130 is part of an extended trypt ophan/arginine zipper which modulates the conformation of the CD loop.