Synapse-associated proteins that are located at the postsynaptic density (PSD) have recently been shown to have a structural role at non-synaptic locations. Here, they act as adaptor proteins between neurotransmitter receptors and the microtubule- or microfilament-based motor-protein complexes that are responsible for transport to the PSD. The use of a common set of proteins that contain multiple domains for protein-protein interactions as both intracellular transport adaptors and synaptic scaffold proteins might contribute to the transport specificity and postsynaptic integration of receptors that underlie synapse formation and plasticity.