Worm Breeder's Gazette 11(4): 64
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
The unc-6 gene encodes an unusual laminin B2 chain (~2.7 kb mRNA). The first 7 exons of the gene have been sequenced and the predicted protein is homologous to the N-terminal domains V and V1 of known laminin B chains (1). Domain V1 is globular and domain V consists of EGF-like repeats. Mutations in the unc-6 gene affect dorsal and ventral cell migration guidance (2). The unc-5 gene has been shown to act in combination with unc-6 to affect dorsal cell migrations. The predicted protein product of the unc-5 gene is a transmembrane receptor (3). Four unc-6 alleles, rh69, rh202, rh204, and rh402, selectively disrupt dorsal cell migrations. We have examined these mutations in detail since they might define a domain of the laminin molecule involved with binding to the unc-5 receptor. Restriction fragment polymorphisms were found in the DNA of strains with the rh202, rh204, or rh402 allele. The polymorphisms were mapped and PCR was used to clone the DNA sequence. As shown below, the three alleles have deletions of the region containing the coding sequences for the second EGF-like repeat in domain V. The fourth allele, rh69, was found to be a point mutation in a splice consensus sequence of the small intron within the V-2 coding sequence. We have not yet looked at the RNA splicing patterns in these strains, however we speculate that the exons for repeats V-1 and V-3 are spliced together, creating a slightly smaller protein lacking repeat V-2. [See Figure 1]