Worm Breeder's Gazette 13(4): 44 (October 1, 1994)
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.
Department of Biological Sciences, University of Alberta, Edmonton, Alberta
We have previously described the cloning and sequencing of fem-2 (WBG 13(1) p59 ).The complete sequence indicates a single open reading frame which encodes a protein of 449 amino acids. A protein sequence database search showed six separate regions of the Fem-2 protein that shared sequence similarity to an uncharacterized human ORF, several protein phosphatase 2C (PP2C) proteins, a predicted protein ( F42G9 .1)from the C. elegans Genome Sequencing project (R.Wilson et al., 1994,Nature 368,32) as well as a protein from Arabidopsis thaliana (ABI1) which is involved in the regulation of the cellular response to abscisic acid. Over a region of 190 amino acids in Fem-2 the human ORF is 37% identical and 56% similar, rat PP2 Cis 37% identical and 49% similar, and ABI1 is 31% identical and 46% similar. The figure below illustrates the position of the six conserved regions (hashed boxes). (see figure) The proteins have been grouped into three classes based on the length of their amino and carboxy termini. Class C proteins are unique in that they have a 10 amino acid acidic peptide between the fourth and fifth conserved regions. The predicted ORF from F42G9 .1contains a two hundred amino acid region that does not show any sequence similarity to any of the other proteins. We have sequenced two mutant alleles of fem-2 ( b245 and q117 ,both are temperature sensitive alleles). The b245 allele contains a G to A change at position 1828, which causes a substitution from glycine to arginine at amino acid 341 in the fourth conserved region. The q117 allele contains a G to A change at position 1242 causing a substitution from glycine to glutamic acid at amino acid 160. Based on the alignment (see figure), Fem-2 seems to fall into a class of protein phosphatases that is distinct from the mammalian or yeast PP2 Chomologues, and is most similar to an uncharacterized human cDNA. The similarity between Fem-2 and these protein phosphatases could suggest that the sex determination pathway is regulated by phosphorylation. If this is the case, we would expect there to be a kinase involved in sex determination as well. So far, there are no identified kinases in this pathway, but it is possible that the kinase is constitutive, and essential, or redundant.