Fig. 1.

Identification of the collagen-interacting ADGRG1/GPR56 NTF in human plasma. (A) GPR56/ADGRG1 schematic with its N-terminal collagen-binding PLL domain and proposed cell movement, force-mediated, tethered agonism activation mechanism. (B) Mass spectrometry tryptic peptide coverage of collagen bead-isolated GPR56 NTF from human plasma. (C) GPR56 NTF from human plasma alongside purified GPR56 rNTF was subjected to collagen-coated bead pull down. Eluted proteins and Sf9 membranes expressing GPR56 were coimmunoblotted with antibodies to detect the GPR56 NTF and CTF. The eluted proteins and Sf9 membranes expressing GPR56 were coimmunoblotted with antibodies to detect the GPR56 NTF (green) and CTF (red). GAIN, G protein-coupled receptor autoproteolysis-inducing domain; 7TM, seven-transmembrane spanning domain.