CELLULAR MEMBRANE PROTEIN ASSAY

摘要

Methods and compositions are provided for determining cell membrane protein populations in the cell membrane of a cell and changes in the population due to changes in the environment or status of the cell. The methods employ a cell having a fusion construct of the cell membrane protein linked to a signal producing peptide through an exofacial protease recognition site or sites. The signal producing peptide is either an enzyme fragment capable of binding to a second enzyme fragment to form an active enzyme when released from the cell membrane or has two binding sites, where the complementary binding entities are related in that a signal is produced when the two entities are in proximity. For the enzyme signal producing peptide, by adding the protease to the cell and the second enzyme fragment and substrate, one can determine the cell membrane protein population and the effect of changes in the cell environment on such population. Similarly, by adding the two entities and any other necessary reagents, a signal is produced whereby one can determine the cell membrane protein population and the effect of changes in the cell environment on such population.