The postsynaptic density

Abstract

The postsynaptic density is a dense, submembranous filamentous structure beneath the postsynaptic membrane. It is a disklike structure that may or may not display perforations. The intimacy of its association with the postsynaptic membrane is reflective of the distribution of some proteins, which are shared between the PSD and postsynaptic membrane, e.g., receptors, ion channels, and adhesion proteins. The PSD displays a complex array of proteins, which are arranged in a hierarchical manner: (1) receptors, ion channels, and adhesion proteins shared with the postsynaptic membrane; (2) scaffold proteins connecting the receptors to each other, to other membrane components, and to the actin cytoskeleton; and (3) the actin-based cytoskeleton, itself. The core structure of the PSD appears to be the scaffold protein postsynaptic density-95 (PSD-95). Another key component of the PSD is the enzyme Ca 2+ /calmodulin-dependent protein kinase II (CaMKII), which is capable of autophosphorylation and, thus, has been implicated in long-term processes. The PSD has been shown to undergo morphological alterations in various parameters with behavioral, hormonal, and electrophysiological inputs. The PSD is important in signal transduction events at the synapse and may be involved in information storage.