Cover picture: Alternative splicing is the major source of polypeptide diversity within the nervous system. Alternative splicing regulates the structure of the C terminus of the NR1 subunit of the NMDA receptor complex and determines the repertoire of cytoplasmic proteins with which NR1 associates. Many NR1-interacting proteins are also alternatively spliced, creating tens of thousands of combinationsof possible NMDA receptor signaling complexes. An article in this week's Journal examines the role of the alternatively spliced C terminus of NR1 in local and long-range NMDA receptor signaling. For details, see the article by Bradley et al. in this issue (pages 1065–1076.