Fig. 7. LIN-2, LIN-7 and LIN-10 form a conserved PDZ-mediated transport complex in polarized cells. (A) Diagram of the three proteins, showing their interactions with each other, which leave all three PDZ domains free to bind ligands. (B ) Diagram of C. elegans vulval precursor epithelial cells. LIN-2, LIN-7 and LIN-10 form a tripartite complex that is essential for targeting of the tyrosine kinase receptor LET-23; proper localization of LET-23 is required for it to detect its ligand, LIN-3, which is present only on the basolateral side (Kaech et al., 1998; Simske et al., 1996). (C) Schematic diagram of the mammalian neuron, showing transport along microtubules of vesicle containing NMDA receptors. The mammalian homolog of LIN-7 (MALS) binds to the C-terminal tail of NMDA receptor subunit 2B, whereas the LIN-10 homolog (MINT1) binds the kinesin superfamily motor protein KIF17. CASK, the LIN-2 homolog, links MALS and MINT1 together. The entire complex, including NMDA-receptor-containing vesicles, is proposed to move along microtubules to the neuronal dendrite (Setou et al., 2000). This complex thus forms a transport system that targets proteins to their appropriate subcellular locations.
