Fig. 6. Lack of orthologs of SOR-1 and SOP-2 in C. briggsae. (A) Schematic representation of sor-1 and its neighboring genes in C. elegans and in C. briggsae. ZK1236.4 corresponds to a transposon in the genome. CBG18140 does not have a clear homolog in C. elegans. Although sor-1 (ZK1236.3) shows some similarity with CBG18142, the latter does not appear to be the ortholog of sor-1 (see Results). (B) Schematic representation of sop-2 and its neighboring genes in C. elegans and in C. briggsae. CBG20941 does not have a clear homolog in C. elegans. sre-52 and sre-54 encode a class of 7 TM chemoreceptors (sre family). (C) Model for the putative SOP-2/SOR-1 complex-mediated transcriptional repression. SOR-1, SOP-2 and perhaps other unidentified components form an RNA-binding complex, which may further recruit chromatin remodeling activity. The RNA components could be involved in targeting the SOP-2/SOR-1 complex to target loci and/or maintaining the integrity of the complex and the distinct nuclear bodies formed by SOR-1 and SOP-2.