Domain architecture of longin proteins. This figure illustrates the common structural elements of longin proteins, including the novel Phytolongins. The central region may be a SNARE motif (yellow) in the longins Ykt6, Sec22 or VAMP7 or a PhyL region in the Phytolongins. Beneath the N-ter (longin) region is a prediction of the tertiary structure of the domain. Note that Ykt6 does not have a CTD region, with a lipid attachment (diamond) while the others possess a transmembrane domain (TMD-red cylinder).