Delineation of additional PSD-95 binding domains within NMDA receptor NR2 subunits reveals differences between NR2A/PSD-95 and NR2B/PSD-95 association.

N-methyl-D-aspartate (NMDA) receptors are clustered at synapses via their association with the PSD-95 (post-synaptic density-95) membrane associated guanylate kinase (MAGUK) family of scaffolding proteins. PSD-95 is the best characterized of this family. It is known to associate with NMDA receptor NR2 subunits via a conserved ES(E/D)V amino acid sequence located at their C-termini and thus to promote the clustering, regulation and the trafficking of assembled NR1/NR2 NMDA receptors at synapses. Here we have investigated in more detail NMDA receptor NR2/PSD-95 protein-protein association. Wild-type NR1 and PSD-95alpha were co-expressed with a series of rodent C-terminal truncated constructs of either NR2A or NR2B subunits in human embryonic kidney (HEK) 293 cells and the association of PSD-95alpha with assembled receptors determined by immunoprecipitation. Additional PSD-95 binding domains that differed between NR2A and NR2B subunits were identified. These domains mapped to the amino acid sequences NR2A (1382-1420) and NR2B (1086-1157). These results suggest that NR2A and NR2B may associate with PSD-95 but with different affinities. This may be important in the determination of the lateral mobility of NMDA receptor subtypes in post-synaptic membranes.

The Mouse Genome Database (MGD): from genes to mice--a community resource for mouse biology.

The Mouse Genome Database (MGD) forms the core of the Mouse Genome Informatics (MGI) system (http://www.informatics.jax.org), a model organism database resource for the laboratory mouse. MGD provides essential integration of experimental knowledge for the mouse system with information annotated from both literature and online sources. MGD curates and presents consensus and experimental data representations of genotype (sequence) through phenotype information, including highly detailed reports about genes and gene products. Primary foci of integration are through representations of relationships among genes, sequences and phenotypes. MGD collaborates with other bioinformatics groups to curate a definitive set of information about the laboratory mouse and to build and implement the data and semantic standards that are essential for comparative genome analysis. Recent improvements in MGD discussed here include the enhancement of phenotype resources, the re-development of the International Mouse Strain Resource, IMSR, the update of mammalian orthology datasets and the electronic publication of classic books in mouse genetics.