The postsynaptic density (PSD) is crucially involved in the structural and functional
organization of the postsynaptic neurotransmitter reception apparatus. Using antisera
against rat brain synaptic junctional protein preparations, we isolated cDNAs coding for
proline-rich synapse-associated protein-1 (ProSAP1), a PDZ-domain protein. This protein
was found to be identical to the recently described cortactin-binding protein-1 (CortBP1).
Homology screening identified a related protein, ProSAP2. Specific antisera raised against a�…

We have recently isolated a novel proline-rich synapse-associated protein-1 (ProSAP1) that
is highly enriched in postsynaptic density (PSD). A closely related multidomain protein,
ProSAP2, shares a highly conserved PDZ (PSD-95/discs-large/ZO-1) domain (80% identity),
a ppI domain that mediates the interaction with cortactin, and a C-terminal SAM (sterile
alpha-motif) domain. In addition, ProSAP2 codes for five ankyrin repeats and a SH3 (Src
homology 3) domain. Transcripts for both proteins are coexpressed in many regions of rat�…