PASSOVER - A GENE REQUIRED FOR SYNAPTIC CONNECTIVITY IN THE GIANT FIBER SYSTEM OF DROSOPHILA

Passover (Pas) flies fail to jump in response to a light-off stimulus. The mutation disrupts specific synapses of the giant fibers (GFs), co mmand neurons for this response. Pas was cloned from a P element-induc ed allele. The cDNA encodes a putative membrane protein of 361 amino a cids. Null, hypomorphic, and dominant alleles were sequenced. In the a dult central nervous system, and in the pupa during GF synapse formati on, Pas is consistently expressed in the GF and in a large thoracic ce ll in the location of its postsynaptic targets. Pas establishes a new gene family. The Drosophila ogre protein, required for postembryonic n euroblast development, is 47% identical; the C. elegans Unc-7 protein, which when mutated alters the connectivity of a few neurons, is 33% i dentical.