Fig. 3. KIF17 and kinesin I cargo interactions compared and contrasted. The signaling scaffold JIP links kinesin I to the transmembrane receptor, ApoER2; the LIN signaling scaffold links KIF17 to the transmembrane protein, NR2B, a subunit of the NMDA-sensitive glutamate receptor. The kinesin-linker interactions are strikingly similar, suggesting a general model for how modular protein-protein interactions underlie kinesin-cargo specificity. In both cases, the kinesin-linker interactions involve a protein-binding module (TPRs or PDZ) designed to recognize specific motifs at the C-termini of partner proteins. In the case of kinesin I, the protein-binding module (TPRs) is in the kinesin tail, and the motif is in the linker; whereas for KIF17, the module (PDZ) is in the linker and the motif in the kinesin.