Identification and characterization of five new subunits of TRAPP

TRAPP (transport protein particle), a multiprotein complex containing ten s ubunits, plays a key role in the late stages of endoplasmic reticulum to Go lgi traffic in the yeast Saccharomyces cerevisiae. We previously described the identification of five TRAPP subunits (Bet5p, Trs20p, Bet3p, Trs23p and Trs33p). Now we report the identification of the remaining five subunits ( Trs31p, Trs65p, Trs85p, Trs120p and Trs130p) as well as an initial characte rization of the yeast complex and its human homologue. We find that three o f the subunits are dispensable for growth and a novel sequence moth is foun d in Bet3p, Trs31p and Trs33p, Furthermore, biochemical characterization of both yeast and human TRAPP suggests that this complex is anchored to a Tri ton X-100 resistant fraction of the Golgi. Differences between yeast and hu man TRAPP as well as the relationship of TRAPP subunits to other docking/te thering factors are discussed.