Determination of interactions between human thrombopoietin and its receptor MPL by yeast two-hybrid system and affinity biosensor

Expression of the soluble extracellular domain of human thrombopoietin receptor using a maltose-binding protein-affinity fusion system

The thrombopoietin (TPO) receptor (Mpl) belongs to the family of ligand-dependent cytokine receptors and plays a functional role in regulating platelet production. The signaling capacity largely depends on the binding of TPO to the extracellular domains of the TPO receptor (Mpl-EC). Because the expression level of Mpl in human tissue is very low, studies on the functional and spatial characteristics of its ligand-binding sites have been limited. In the present study, we report the expression and purification of Mpl-EC as a fusion with the maltose-binding protein (MBP), designated MBP-Mpl-EC. MBP-Mpl-EC was expressed in the cytoplasm of Escherichia coli as a soluble fusion protein. Specific binding of TPO to purified MBP-Mpl-EC was demonstrated by a dot-blot assay and surface plasmon resonance. We conclude that bacterial expression of MBP-Mpl-EC yields large amounts of protein with correct folding and that it can be used for further structure and function analyses.

Survey of the year 2000 commercial optical biosensor literature

We have compiled a comprehensive list of the articles published in the year 2000 that describe work employing commercial optical biosensors. Selected reviews of interest for the general biosensor user are highlighted. Emerging applications in areas of drug discovery, clinical support, food and environment monitoring, and cell membrane biology are emphasized. In addition, the experimental design and data processing steps necessary to achieve high-quality biosensor data are described and examples of well-performed kinetic analysis are provided.