AN ANKYRIN-RELATED GENE (UNC-44) IS NECESSARY FOR PROPER AXONAL GUIDANCE IN CAENORHABDITIS-ELEGANS

Caenorhabditis elegans unc-44 mutations result in aberrant axon guidance and fasciculation with inappropriate partners. The unc-44 gene was cloned by transposon tagging, and verified by genetic and molecular analyses of six transposon-induced alleles and their revertants. Nucleotide sequence analyses demonstrated that unc-44 encodes a series of putative ankyrin-related proteins, including AO49 ankyrin (1815 aa, 198.8 kD), AO66 ankyrin (1867 aa, 204 kD), and AO13 ankyrin (less than or equal to 4700 aa, less than or equal to 517 kD). In addition to the major set of similar to 6 kb alternatively spliced transcripts, minor transcripts were observed at similar to 3, 5, 7, and 14 kb. Evidence is provided that mutations in the similar to 14-kb AO13 ankyrin transcript are responsible for the neuronal defects. These molecular studies provide the first evidence that ankyrin-related molecules are required for axonal guidance.