FUNCTIONAL EXPRESSION OF RAT SYNAPSE-ASSOCIATED PROTEINS SAP97 AND SAP102 IN DROSOPHILA DLG-1 MUTANTS - EFFECTS ON TUMOR SUPPRESSION AND SYNAPTIC BOUTON STRUCTURE

The synapse-associated proteins SAP97 and SAP102 are mammalian protein s that are structurally related to the Drosophila tumor suppressor pro tein DlgA. Previous analyses revealed that DlgA is essential for the i ntegrity of epithelia and neuromuscular synapses. Here we show that sy naptic bouton structure is severely affected in mutant larvae carrying the dlg-1(XI-2) allele. We have tested SAP97 and SAP102 for functiona l homology to DlgA by heterologous expression in Drosophila. Both SAP9 7 and SAP102 can suppress tumor formation in dig-1 mutant flies and mi mic DlgA at larval neuromuscular junctions. Neuronal expression of SAP 97 or SAP102 is required for morphological restoration of synaptic bou tons, indicating that presynaptic DlgA function is essential for estab lishing structurally intact motor nerve terminals at larval neuromuscu lar junctions. (C) 1997 Elsevier Science Ireland Ltd.