High-Throughput Quantification of Surface Protein Internalization and Degradation

Cell surface proteins are key regulators of fundamental cellular processes, and therefore often at the root of human diseases. Thus, a large number of targeted drugs which are ap-proved or under development act upon cell surface proteins. While down-regulation of sur-face proteins by many natural ligands is well established, the ability of drug candidates to cause internalization or degradation of the target is only recently moving into focus. This property is important both for the pharmacokinetics and pharmacodynamics of the drug, but may also constitute a potential resistance mechanism. The enormous numbers of drug can-didates targeting cell surface molecules, comprising small molecules, antibodies, or alterna-tive protein scaffolds, necessitate methods for the investigation of internalization and degra-dation in high throughput. Here, we present a generic high-throughput assay protocol, which allows the simultaneous and independent quantification of internalization and degradation of surface proteins ...