Figure 7

Model for the conserved structure and function of the TRAPPI and TRAPPII complexes. TRAPP complexes mediate exocytic trafficking from the ER, through the Golgi, to the plasma membrane. The TRAPPI complex (left) is shown as a quadrilateral with subunits indicated as triangular sections. Subunits are 3-Bet3, 5-Bet5, 20-Trs20, 23-Trs23, 31-Trs31, 33-Trs33. The Bet3 family (3, 31, 33), are shown as identically light gray triangular sections. The Bet5 family (5,20,23) are shown as identically dark gray triangular sections. The displayed arrangement of components is derived from Kim et al., 2006 [17]. The TRAPPII complex (right) includes all the TRAPPI components plus the three TRAPPII-specific subunits shown in the trapezoidal shape above TRAPPI. In both complexes, subunits essential for viability are labeled in black letters, while non-essential subunits are shown in gray letters. Functionally, TRAPPI is the GEF for Ypt1, the GTPase (GTPases are shown as triangles) that regulates entry into the Golgi, whereas TRAPPII is the GEF for Ypt31/32, the GTPases that regulate exit from the Golgi [16]. All shapes have areas proportional to the corresponding amino acid lengths, except for Trs85, which is larger than shown.