Fig. 5. Schematic representation of C. elegans SDN-1 and sequence comparison of its transmembrane and cytoplasmic domains with those of other species. (A) Model of SDN-1 showing its type I transmembrane protein nature. The locations of the GAG attachment sites in the ectodomain (white arrowheads), including a putative site closer to the transmembrane region, are shown. The postulated phosphorylated serine residue of the cytoplasmic domain (Ser^P) and the location of primer used to analyze wild-type and sdn-1 (ok449) worm strains (black arrows). The lower model shows the most likely form of the deleted SDN-1 protein, as deduced from sdn-1 (ok449) cDNA sequencing. (B) SDN-1 sequence for the conserved transmembrane and cytoplasmic domains is shown aligned to other syndecan sequences. A consensus sequence arose when the SDN-1 sequence was compared with syndecan-1, -2, -3 and -4 from different species.