“…In planaria, silencing in response to ingested dsRNA can occur in most tissues (Rouhana et al, 2013) and weak homologs of SID-1 are present (Zayas et al, 2005) but the roles of these homologs in the uptake of dsRNA are yet to be evaluated. Finally, a mammalian homolog of SID-1, SidT2, is a lysosomal membrane protein (Jialin et al, 2010), which is in contrast to the reported plasma membrane localization of C. elegans SID-1 (Winston et al, 2002), and mouse knockouts of SidT2 have impaired glucose tolerance (Gao et al, 2013), which is in contrast to the lack of obvious defects in C. elegans that lack SID-1 (Winston et al, 2002), suggesting that SID-1 and its mammalian homologs also have alternative function(s). An intriguing clue to such alternative functions comes from a close inspection of sequence similarity, which suggests that both SID-1 and CHUP-1 have a domain with weak similarity to hydrolases (Pei et al, 2011).…”