HIKARU-GENKI, A CNS-SPECIFIC GENE IDENTIFIED BY ABNORMAL LOCOMOTION IN DROSOPHILA, ENCODES A NOVEL TYPE OF PROTEIN

We have identified a gene, hikaru genki (hig), whose mutant phenotype includes abnormal locomotor behavior. Mutant first instar larvae have uncoordinated movements, and both larvae and adults have reduced locomotion. Sequence analyses revealed that this gene encodes a novel type of protein with a signal sequence, but without transmembrane regions. One of its domains has similarities with immunoglobulin domains; three or four regions are similar to a complement-binding domain found in complement-related proteins and selectins. In situ hybridization to embryos revealed that accumulation of the hig transcripts is restricted to subsets of cells in the CNS. Our data suggest that hig has a role in the development of CNS functions involved in locomotor activity.