solid phase assay avexis PSI-MI 2015-06-01T15:05:13Z Low-affinity interaction detection method designed specifically to detect interactions between extracellular proteins. Recombinant soluble fragments of these proteins are produced in a (generally) mammalian expression cell line and secreted into the medium and produced in two forms: a biotinylated bait which can be captured on a streptavidin-coated solid phase suitable for screening, and a pentamerised enzyme-tagged (beta-lactamase) prey. The bait and prey proteins are presented to each other in a binary fashion to detect direct interactions between them, similar to a conventional ELISA. The pentamerisation of the proteins in the prey is achieved through a peptide sequence from the cartilage oligomeric matrix protein (COMP) and increases the local concentration of the ectodomains thereby providing significant avidity gains to enable even very transient interactions to be detected. By normalising the activities of both the bait and prey to predetermined levels prior to screening, interactions having monomeric half-lives of 0.1 sec can be detected with low false positive rates. ppm MI:2189 AVidity-based EXtracellular Interaction Screen avidity-based extracellular interaction screen avexis