Sterol transporter that transfers sterols between membranes; binds phosphatidylserine (PS) and synergistically to membranes containing both PS and ergosterol; may coordinate formation of contact sites between organelles; localizes to ER-mito contact sites in a Tom70p- and Tom71p-dependent manner, and to ER-vacuole sites, in a Vac8p-dependent manner; mitochondrial localization requires the GRAM domain; one of six StART-like (VASt) domain-containing proteins in yeast; conserved across eukaryotes