Ykt6 forms complexes with syntaxin-5 (Qa), GS28 (Qb) and either Bet1 (Qc) or GS15 (Qc). This complex regulates the early secretory pathway of eukaryotic cells at the level of the transport from the ER-Golgi intermediate compartment (ERGIC) to the cis-Golgi and transport from the trans-Golgi network to the cis-Golgi, respectively. Ykt6 is a member of the R-SNARE subfamily of SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins which contain coiled-coil helices (called SNARE motifs) that mediate the interactions between SNARE proteins, and a transmembrane domain. The SNARE complex mediates membrane fusion, important for trafficking of newly synthesized proteins, recycling of pre-existing proteins and organelle formation. SNARE proteins are classified into four groups, Qa-, Qb-, Qc- and R-SNAREs, depending on whether the residue in the hydrophilic center layer of the four-helical bundle is a glutamine (Q) or arginine (R). Qa-, as well as Qb- and Qc-SNAREs, are localized to target organelle membranes, while R-SNARE is localized to vesicle membranes. They form unique complexes consisting of one member of each subgroup, that mediate fusion between a specific type of vesicles and their target organelle. Their SNARE motifs form twisted and parallel heterotetrameric helix bundles.
Jiyao W et al.(2023). "The conserved domain database in 2023.",