Vacuolar H+-ATPases (V-ATPases) are ATP-dependent proton pumps composed of peripheral V1 sector and membrane-bound V0 sector. It is localized at membranes of intracellular acidic organelles and plasma membranes of various cell types. By virtue of its regulation in acidification, V-ATPase is required for many intracellular processes such as receptor-mediated endocytosis and protein sorting. We have characterized the E subunit of V-ATPase in C. elegans. This subunit is one of the most well conserved subunits sharing approximately 57% identity with the human homologue, ATP6E. Green fluorescent protein (GFP) and whole-mount immunostaining analyses showed that V-ATPase E subunit (
vha-8) abundantly expresses in the H-shaped excretory cell, consistent with the expression patterns observed for other V-ATPase subunits. RNA mediated interference targeted to
vha-8 resulted in embryonic and larval lethality indicating that
vha-8 is essential during early developmental processes. Recently, we have isolated a deletion mutant of
vha-8, which shows embryonic lethality. We are currently characterizing this mutant in order to elucidate the functional roles of V-ATPase during early embryogenesis as well as in receptor-mediated endocytosis.