Oxysterol binding protein related proteins (ORPs) constitute an enigmatic family of intracellular lipid receptors related through a shared lipid binding domain. Emerging evidence suggests that ORPs conjoin lipid metabolism with membrane transport. Current data imply that the yeast ORP, Kes1p, is a negative regulator of Golgi derived vesicular transport mediated by the essential phosphatidylinositol/phosphatidylcholine transfer protein Sec14p. Inactivation of Kes1p function allows for restoration of growth and vesicular transport in cells lacking Sec14p function, and Kes1p function in this regard can be complemented by human ORP1S. Recent studies have determined that Kes1p and ORP1S both bind phospholipids as ligands. To explore the function of distinct linear segments of ORP1S in phospholipid binding and vesicular transport regulation we generated a series of 15 open reading frames coding for diagnostic regions within ORP1S. Purified versions of these ORP1S deletion proteins were characterized in vitro and allowed for the identification of a nominal phospholipid binding region. The in vitro analysis was interpreted in the context of in vivo growth and vesicle transport assays for analytic members of the ORP1S deletion set. The results determined that phospholipid binding domain per se was insufficient for ORP1S inhibition of vesicular transport and that CPY and invertase transport from the Golgi may be regulated differentially by specific regions of ORP1S/Kes1p.