A novel assay for assessing juxtamembrane and transmembrane domain interactions important for receptor heterodimerization.

Understanding the basis of specificity in receptor homodimerization versus heterodimerization is essential in determining the role receptor plays in signal transduction. Specificity in each of the interfaces formed during signal transduction involves cooperative interactions between receptor extracellular, transmembrane (TM), and cytoplasmic domains. While methods exist for studying receptor heterodimerization in cell membranes, they are limited to either TM domains expressed in an inverted orientation or capture only heterodimerization in a single assay. To address this limitation, we have developed an assay (DN-AraTM) that enables simultaneous measurement of homodimerization and heterodimerization of type I receptor domains in their native orientation, including both soluble and TM domains. Using integrin αIIb and RAGE (receptor for advanced glycation end products) as model type I receptor systems, we demonstrate both specificity and sensitivity of our approach, which will provide a novel tool to identify specific domain interactions that are important in regulating signal transduction.