Figure 1

(a) Comparison of domain structures of engineered ectodomain of postsynaptic cell adhesion molecules. WT, wild type; YFP, yellow fluorescent protein; RFP, red fluorescent protein (TagRFP-T); H, hexa- or octa-His tag; OG, O-glycosylation rich domain; TMD, transmembrane domain; CD, cytoplasmic domain; GPI, glycosylphosphatidylinositol anchoring motif; GS, glycine-serine linker; AP, biotin acceptor peptide (AviTag). (b) Structure of optimized expression vector. Bicistronic expression of BirA for mass production of in vivo biotinylated postsynaptic CAMs. SS, signal sequence; HA, hemagglutinin affinity tag; H6, hexa-His tag; H8, octa-His tag; IRES, internal ribosome entry site. The SS, HA and H6 can vary depending upon the type of the postsynaptic CAMs. (c) Schematic structure of excitatory and inhibitory artificial dendrites displaying C-terminally tagged ectodomains of postsynaptic NL1 homodimer (NL1-R) and Slitrk3 monomer (SL3-R). The in vivo biotinylated fluorescence tagging module enables oriented immobilization of the ectodomains on streptavidin (SAV) surface. The structure of NL1 was modelled after NL1 (PDB ID, 3BIX)²⁰ while the structure of Slitrk3 (27–627 residues) was predicted using Slitrk1 (PDB ID, 4RCW)³¹ as a template by the RaptorX server³², showing two LRR1 and LRR2 domains.