Fig. 1. Structure of the dgn-1 gene and product. (A) Coding (gray) and non-coding (white) exons of dgn-1; regions corresponding to - and ß-DG, the site of /ß cleavage in vertebrates (arrowhead), and the extent of the cg121 deletion are indicated. (B) Three regions of similarity to vertebrate (mouse) and Drosophila DGs were identified, corresponding to the N-terminal domain of -DG, the C-terminal region of vertebrate -DG plus extracellular region of ß-DG (core domain), and the ß-DG cytoplasmic domain. A transmembrane (TM) region follows the core. Amino acids retained in a majority of the sequences are shown in color (N-terminal, purple; core and transmembrane, green; cytoplasmic, red), similar residues in gray. Two additional predicted DG-like proteins in C. elegans, DGN-2 and DGN-3, contain a core domain but lack similarity to DG outside of the core (not shown). Conserved cysteine pairs () in N-terminal and core domains, conserved predicted N-glycosylation sites (•) in the core domain, and the /ß cleavage sitein vertebrate DG () are indicated. A 20-residue threonine-rich region in the DGN-1 N-terminal domain may function as a mucin-like region. Residues mediating interaction of the ß-DG cytoplasmic tail with WW/SH3 proteins such as dystrophin are indicated (asterisks). (C) Pairwise sequence similarity (% identity/% similarity) between conserved regions. Regions of similarity were identified by BLAST (Altschul et al., 1990) and sequence alignments constructed using Clustal W (Thompson et al., 1994).