Trafficking Protein Particle Complex 5 (TRAPPC5)

The six different vertebrate TRAPP subunits whose structures have been solved can be divided into two families: the bet3 family composed of TRAPPC3, TRAPPC5 and TRAPPC6 and the sedlin family composed of TRAPPC1, TRAPPC2 and TRAPPC4.However, TRAPPC5/Trs31p and TRAPPC6/Trs33p, the two other TRAPP subunits that are structural homologues of TRAPPC3 (9,18,19,22), do not have such a channel, and it is unclear why only the TRAPPC3 protein would have it.TRAPPC3 interacts with TRAPPC6 or TRAPPC5 using a common surface, and each heterodimer interacts with another subunit side by side to form flat subcomplexes.A sequence alignment reveals that vertebrate TRAPPC5 contains a unique insertion of the amino acid residues SVPK compared with yeast Trs31p.