http://orcid.org/0000-0002-1925-636X
Figures & data
Figure 1. A schematic illustration of the mode of YKT6 function in autophagosome (AP)-lysosome (L) fusion. (a) The model of Matsui et al. [Citation47] for HeLa cells, in which STX17 and YKT6 contributes to fusion in separate SNARE complexes I (comprized of autophagosomal STX17, SNAP29, and lysosomal VAMP7) and II (comprized of autophagosomal Ykt6, Snap29 and lysosomal Stx7). (b) The model of Takáts et al. [Citation48] in Drosophila cells, in which Ykt6 is recruited onto lysosomes and regulates fusion in a noncanonical manner by engaging Snap29 and HOPS, but is ultimately displaced from the final SNARE fusion complex by Vamp7. (c) Another hypothetical model for Ykt6 action, in which YKT6 is recruited onto autophagosomes (instead of lysosomes) prior to STX17 translocation to autophagosomes. YKT6 on autophagosomes could mediate fusion on its own by engaging SNAP29 and a lysosomal Qa SNARE (such as STX7), albeit at a low basal level (dotted arrow). However, when STX17 is recruited onto autophagosomes during autophagy induction, it would take over as the main SNARE that drives fusion, when STX17-SNAP29 forms a SNARE complex in trans with lysosomal VAMP7 (perhaps with YKT6 displaced by VAMP7). (d) A schematic diagram of the domain structure of YKT6, which harbors a C-terminal sequence of -CCAIM. When the more distal Cys residue is farnesylated (green), the molecule’s SNARE domain folds back onto the N-terminal longin domain, forming the ‘closed’ form of YKT6 that remains cytoplasmic. Palmitoylation (blue) at the other Cys results in an ‘open’ conformation of YKT6 that becomes tail anchored to a membrane.
![Figure 1. A schematic illustration of the mode of YKT6 function in autophagosome (AP)-lysosome (L) fusion. (a) The model of Matsui et al. [Citation47] for HeLa cells, in which STX17 and YKT6 contributes to fusion in separate SNARE complexes I (comprized of autophagosomal STX17, SNAP29, and lysosomal VAMP7) and II (comprized of autophagosomal Ykt6, Snap29 and lysosomal Stx7). (b) The model of Takáts et al. [Citation48] in Drosophila cells, in which Ykt6 is recruited onto lysosomes and regulates fusion in a noncanonical manner by engaging Snap29 and HOPS, but is ultimately displaced from the final SNARE fusion complex by Vamp7. (c) Another hypothetical model for Ykt6 action, in which YKT6 is recruited onto autophagosomes (instead of lysosomes) prior to STX17 translocation to autophagosomes. YKT6 on autophagosomes could mediate fusion on its own by engaging SNAP29 and a lysosomal Qa SNARE (such as STX7), albeit at a low basal level (dotted arrow). However, when STX17 is recruited onto autophagosomes during autophagy induction, it would take over as the main SNARE that drives fusion, when STX17-SNAP29 forms a SNARE complex in trans with lysosomal VAMP7 (perhaps with YKT6 displaced by VAMP7). (d) A schematic diagram of the domain structure of YKT6, which harbors a C-terminal sequence of -CCAIM. When the more distal Cys residue is farnesylated (green), the molecule’s SNARE domain folds back onto the N-terminal longin domain, forming the ‘closed’ form of YKT6 that remains cytoplasmic. Palmitoylation (blue) at the other Cys results in an ‘open’ conformation of YKT6 that becomes tail anchored to a membrane.](/cms/asset/e7f1deb2-f612-4048-84c4-93fedf0c1698/kaup_a_1532261_f0001_oc.jpg)