NTR: glycogen granule-autophagosome adaptor activity

[Antonialock]

Please provide as much information as you can:

• Suggested term label:

glycogen granule-autophagosome adaptor activity

• Definition (free text) The binding activity of a molecule that brings together a glycogen granule and an autophagosome during glycophagy, the autophagy of glycogen.

• Reference, in format PMID:####### 38832010

• Gene product name and ID to be annotated to this term

atg45 YIL024C

• Parent term(s)

GO:0160183

• Any other information

in https://www.sciencedirect.com/science/article/pii/S2589004224010320?via%3Dihub the authors term atg45 an autophagy receptor for glycogen

section: Atg45 functions as a glycogen receptor ...Atg45 binds to glycogen through the GBD identified within Atg45 1-96 ...the C-terminal half of Atg45 is required for sequestration into autophagosomes, ...These results suggest that an AIM is present within the C-terminal half of Atg45. We identified 127YVNL130 as the sole candidate for an AIM within the region. To investigate whether this site functions as AIM, we carried out co-immunoprecipitation of GFP-Atg8 and Atg45-FLAG using the GFP-Trap magnetic agarose system. While WT Atg45 exhibited binding to Atg8, the alanine-substituted mutant of the putative AIM (Y127A and L130A, herein Atg45AIMm) had a low binding ability

Discussion: We found that Atg45 is important for glycophagy and that this protein binds to both glycogen and Atg8. We therefore conclude that Atg45 functions as a glycophagy receptor.

[pgaudet]

Hi @Antonialock

Is this a receptor or an adaptor? Could this activity be a child of cargo receptor activity?

Thanks, Pascale

[Antonialock]

I don't think so? I think cargo receptor refers to endocytic things? (atg45 is also not transmembrane spanning)

doesn't GO:0160183 autophagosome-membrane adaptor activity look correct? ohh I suppose it doesn't link the autophagosome to a membrane, it links it to a macromolecular complex?

[Antonialock]

table 1 here might be of interest https://febs.onlinelibrary.wiley.com/doi/full/10.1111/febs.15824 Table 1. Selective autophagy types and corresponding receptors.

[ValWood]

~This is more of a sequestering activity, maybe? GO:0140313 molecular sequestering activity~

[pgaudet]

@marcfeuermann I notice that we we don't have a term for 'autophagy receptor'; is this missing in the ontology ? If not, how is this supposed to be captured?

[marcfeuermann]

There are tens of thousands of papers about autophagy and we could create hundreds of new terms about it. So, many terms are probably still missing, especially since it is a hot topic and everyone wants to find a new autophagy-related mechanism. About this specific request, personally, I wouldn't call these receptors. Can we talk about mitochondria or endoplasmic reticulum receptors ? It seems rather that these molecules act as adaptors between ATG8 proteins linked to the autophagosome membrane and macromolecules or organelles (via proteins present in the membranes of the organelles). I'd go for something along the lines of "cargo-autophagosome adaptor activity", as Antonia first suggested. After that, if you think you need a term for each type of autophagy, you can create all the corresponding children (glycophagy, aggrephagy, reticulophagy, mitophagy, lipophagy, ...). To add more fuel to my fire, some children terms already exist: GO:0140580 mitochondrion autophagosome adaptor activity GO:0140506 endoplasmic reticulum-autophagosome adaptor activity GO:0160183 autophagosome-membrane adaptor activity

And we have the following related process term that should probably be obsoleted: GO:0061753 substrate localization to autophagosome I hope this will be helpful to take a decision. Best regards, Marc.

[ValWood]

I agree that "cargo receptor" sounds appropriate. We could broaden the definition from

Binding specifically to a substance (cargo) and a membrane to deliver it to a transport vesicle [or to a vacuole]. PMID:15239958 PMID:27903609

This could be used for Antonia's example and we could also move autophagosome-membrane adaptor activity (GO:0160183) under such term.

However, we get in a mess because currently autophagosome-membrane adaptor activity (GO:0160183) are types of protein-membrane adaptor activity (GO:0043495) -- | -- The binding activity of a molecule that brings together a protein or a protein complex with a membrane, or bringing together two membranes, either via membrane lipid binding or by interacting with a membrane protein, to establish or maintain the localization of the protein, protein complex or organelle.

which seems to be more about normal location than a substrate for degradation. so this definition would also need to b e broadened....