An important finding of our study was the enrichment of essential
proteins as well as proteins that affect fat accumulation in C. elegans.
Experiments in the fruit fly Drosophila melanogaster demonstrate that
lipid droplet associated proteins are required to support early development
[2]. It is important to note that the fat accumulation defects are not
necessarily direct effect of lipid droplets, for example, act-5(RNAi)
worms likely have poor nutrient absorption due to defects in intestinal
microvilli [58]. A limitation of our studywas thatwe identified relatively
fewlipidmetabolismproteins. For example,we did not identify DGAT2,
which has been shown to associate with C. elegans lipid droplets at the
ER interface during lipid droplet expansion [20]. Similarly, the atlastin
GTPase [17], the lipase ATGL-1 [22], and the CGI-58 homolog coactivator
LID-1 [22] did not appear in the proteome of isolated lipid
droplets from wild type or daf-2 mutants. Perhaps these proteins are
of relatively low abundance, or alternatively, our purification method
may not have allowed for the retention of loosely associated lipid droplet
proteins or of proteins that only associate with lipid droplets at the
ER interface during lipid droplet expansion.