Worm Breeder's Gazette 11(3): 29
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.
We have been cloning the maternal-effect lethal gene par-2. Embryos from a homozygous par-2 mother undergo symmetric and synchronous cleavages, a failure to localize P granules properly, a low expression (20%) of gut granules, and no morphogenesis (Kemphues et al. Cell 52:1988). The role of the wild type par-2 gene, as well as the other par genes, is therefore thought to be in the organization of the cytoplasm and the proper partitioning of cytoplasmic components in early embryogenesis. We have previously described the identification of a par-2 allele specific polymorphism, which consists of a 3 kb deletion in the allele it46. We have also shown that the DNA contained within this deletion identifies a 2.3 kb oocyte specific message when used to probe a Northern blot containing RNA isolated from fem-2 (sperm minus) and glp-1 (germline minus) animals (1989 CSH C. elegans meeting). Because this message seemed likely to be the par-2 message, we used the same probe to isolate cDNA's from the Schauer, Kim, Barstead, and Martin cDNA libraries. Although none of these cDNA's are full length, we are within a few hundred base pairs of the complete message. Hybridization experiments with 5' and 3' specific cDNA probes indicate that the it46 polymorphism deletes coding sequences found in this cDNA. These data strongly support the notion that this cDNA clone represents the par-2 message. We have sequenced 2.1 kb of this cDNA clone and searched several databases with the predicted protein product--however, no homologous proteins were found. The one notable feature of this sequence is the presence of an ATP-binding site of the myosin class. The figure below shows the ATP-binding site consensus sequence, the par-2 putative ATP- binding site, as well as other members of this class of proteins. While we don't yet understand the role this protein plays in early development, we are intrigued by the presence of the ATP-binding site which is consistent with a role for par-2 in cytoplasmic sorting during early cleavage divisions. [See Figure 1]