M. Irie, Y. Hata, M. Takeuchi, K. Ichtchenko, A. Toyoda, K. Hirao, Y. Takai, T. W. Rosahl, T. C. Südhof ^*

PSD-95 is a component of postsynaptic densities in central synapses. It contains three PDZ domains that localize N-methyl-D-aspartate receptor subunit 2 (NMDA2 receptor) and K⁺ channels to synapses. In mouse forebrain, PSD-95 bound to the cytoplasmic COOH-termini of neuroligins, which are neuronal cell adhesion molecules that interact with -neurexins and form intercellular junctions. Neuroligins bind to the third PDZ domain of PSD-95, whereas NMDA2 receptors and K⁺ channels interact with the first and second PDZ domains. Thus different PDZ domains of PSD-95 are specialized for distinct functions. PSD-95 may recruit ion channels and neurotransmitter receptors to intercellular junctions formed between neurons by neuroligins and -neurexins.

M. Irie, M. Takeuchi, A. Toyoda, K. Hirao, Takai Biotimer Project, ERATO, Japan Science and Technology Corporation, 2-2-10, Murotani, Nishi-ku, Kobe, 651-22, Japan. Y. Hata, Howard Hughes Medical Institute and Department of Molecular Genetics, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75235-9050, USA, and Takai Biotimer Project, ERATO, Japan Science and Technology Corporation, 2-2-10, Murotani, Nishi-ku, Kobe 651-22, Japan.
K. Ichtchenko, T. W. Rosahl, T. C. Südhof, Howard Hughes Medical Institute and Department of Molecular Genetics, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75235-9050, USA.
Y. Takai, Takai Biotimer Project ERATO, Japan Science and Technology Corporation, 2-2-10, Murotani, Nishi-ku, Kobe 651-22, Japan, and Department of Molecular Biology and Biochemistry, Osaka University Medical School, Suita 565, Japan.
^*   To whom correspondence should be addressed.