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 (< or = 4700 aa, < or = 517 kD). In addition to the major set of approximately 6 kb alternatively spliced transcripts, minor transcripts were observed at approximately 3, 5, 7, and 14 kb. Evidence is provided that mutations in the approximately 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.