Table 1.

Autophagosomal proteins and their association with microtubules

ProteinRole in autophagy1Link with microtubulesReferences2
ATG proteins
    LC3 (ATG8)Two post-translationally modified forms: cytosolic LC3-I and membrane-bound LC3-II (LC3–PtdEtn) (autophagosome)Contributes to the closure of the autophagosome membraneSubunit of the neuronal microtubule-associated proteins MAPlA and MAPlB.Co-purifies with Taxol-assembled rat MTs.Binds to tubulin through ionic interactions.LC3-I binds to the labile MT fraction, LC3-II to the stable MT fraction.Participates in minus-end- and plus-end-directed autophagosome transport.Mann and Hammarback, 1994Geeraert et al., 2010Kimura et al., 2008; Pankiv et al., 2010</citref>
    ATG5–ATG12Contribute to the expansion and the closure of the autophagosome membrane together with ATG16LCo-purify with labile MTs in starved cells.Geeraert et al., 2010
    Beclin 1 (ATG6)Participates in a complex with the class III phosphoinositide 3-kinase VPS34, ATG14L, VPS15 and AMBRA1Contributes to the initiation of autophagosome formationBinds to MTs through interactions with AMBRA1 and DLC1 with Bim and DLC1.Sequestered on MTs at the basal level and relocalized to phagophores under starvationDi Bartolomeo et al., 2010; Luo et al., 2012Di Bartolomeo et al., 2010; Luo et al., 2012
    WIPI1 (ATG18)Binds to PtdIns3P on phagophoresBinds to MTs through recruitment into mobile pre-autophagosomal structures; co-purifies with labile MTs in starved cellsGeeraert et al., 2010
    ULK1/UNC-51 (ATG1)Phosphorylates raptor and AMBRA1Binds to a kinesin heavy chain adaptor in neuronsPhosphorylates AMBRA1 to release AMBRA1 and Beclin 1 from their interaction with MTsToda et al., 2008 Di Bartolomeo et al., 2010
Non-ATG proteins
    p62Autophagy substrate, interacts with ubiquitinCo-purifies with both labile and stable microtubules in starved cellsGeeraert et al., 2010
    AMBRA1Participates in a complex with class III PI 3-kinase VPS34, ATG14L, VPS15 and Beclin 1Contributes to the initiation of autophagosome formationMediates binding of Beclin 1 to MTs through interaction with dynein light chain; released with Beclin 1 after phosphorylation by ULK1 upon induction of autophagyDi Bartolomeo et al., 2010
    FYCO1Interaction with LC3, RAB7 and PtdIns3PPromotes plus-end-directed transport of autophagic vesiclesPankiv et al., 2010
  • 1 For specific references, see the main text (for reviews, see Kroemer et al., 2010; Mizushima et al., 2011; Singh and Cuervo, 2011; Yang and Klionsky, 2010).

  • 2 Cited references only correspond to the interactions with microtubules (MTs).