The Caenorhabditis elegans (Ce)
glp-1 gene encodes a Notch-like receptor. We have cloned
glp-1 from C. briggsae (Cb) and C. remanei (Cr), two Caenorhabditis species that have diverged from C. elegans by roughly 20-40 million years. By sequence analysis, we find that the Cb-GLP-1 and Cr-GLP-1 proteins have retained the same motif architecture as Ce-GLP-1, including number of domains. In addition, two regions (CC-linker and regions flanking the ANK repeats) are as highly conserved as regions previously recognized as essential for signaling (e.g., ANK repeats). Phylogenetic analysis of
glp-1 sequences suggests a C. briggsae/C. remanei clade with C. elegans as a sister taxon. Using RNAi to test biological functions, we find that
Ce-glp-1,
Cb-glp-1, and
Cr-glp-1 are all required for proliferation of germline stem cells and for specifying blastomere fates in the embryo. In addition, certain biological roles of
Cb-glp-1, e.g., in the vulva, have diverged from those of
Ce-glp-1 and
Cr-glp-1, suggesting a change in either regulation or function of the
Cb-glp-1 gene during evolution. Finally, the regulation of
glp-1 mRNA, previously analyzed for
Ce-glp-1, is conserved in
Cb-glp-1, and we identify conserved 3' UTR sequences that may serve as regulatory elements.