Three proteins involved in Caenorhabditis elegans vulval invagination are similar to components of a glycosylation pathway

We have molecularly analyzed three genes, sqv-3, sqv-7: and sqv-8, that are required for wild-type vulval invagination in Caenarhabditis elegans. The predicted SQV-8 protein is similar in sequence to two mammalian beta(1,3)-g lucuronyltransferases, one of which adds glucuronic acid to protein-linked galactose-beta(1,4)-N-acetylglucosamine. SQV-3 is similar to a family of gl ycosyltransferases that includes vertebrate beta(1,4)-galactosyltransferase s, which create galactose-beta(1,4) -N-acetylglucosamine linkages. One mode l is therefore that SQV-8 uses a SQV-3 product as a substrate. SQV-7 is sim ilar to members of a family of nucleotide-sugar transporters. The sqv genes therefore are likely to encode components of a conserved glycosylation pat hway that assembles a C. elegans carbohydrate moiety, the absence of which perturbs vulval invagination.