TREM2 and frontotemporal dementia: In the second set of constructs, we co-expressed full-length BRI2 tagged with a 3xFLAG at the N-terminus along with various variants of TREM2, including full-length TREM2, TREM2-δIg-like (lacking the Ig-like domain of TREM2 spanning amino acids 29-112), TREM2-CTF (comprising amino acids 158-230), TREM2-W198Ter (encoding the TREM2 W198Ter variant, a truncated TREM2 protein lacking the intracellular domain associated with FTD when homozygous (Giraldo et al, 2013), and Trem2-δ/α-site (lacking amino acids 152–163, including the α-secretase cleavage site).