GO:0000030 | mannosyltransferase activity , PTN002003922

[ValWood]

• PTHR ID & PTN node:

GO:0000030 | mannosyltransferase activity | IBA with S000000557 , PTN002003922 | contributes_to | GO_REF:0000033

• Sequences with problematic annotation (ID + gene/protein name):

https://www.pombase.org/gene/SPCC1919.02 pbn1/ PIG-X
https://www.yeastgenome.org/locus/S000000557 Pbn1

• Type of Issue: Erroneous source or erroneous propagation, or other issue

Annotation

@edwong57

• Add the label 'high priority' if needed. Generally high priority issues affect a lot of proteins, and annotations are incorrect (as opposed to just imprecise).

[ValWood]

sorry the details:

UniProt Human PIG-M concurs
Mannosyltransferase involved in glycosylphosphatidylinositol-anchor biosynthesis. Transfers the first alpha-1,4-mannose to GlcN-acyl-PI during GPI precursor assembly.
PMID: 11226175

PIG-M (gpi14) and PIG-X (Pbn1)

are the 2 members of
GO:1990529 glycosylphosphatidylinositol-mannosyltransferase I complex

PIG-X appears to be the regulatory protein
https://www.ebi.ac.uk/interpro/entry/InterPro/IPR013233/

see geneontology/go-ontology#28214

[edwong57]

@ValWood What do you think is an appropriate replacement for 'mannosyltransferase activity' for PBN1? GO:0005198 structural molecule activity?

[ValWood]

I was thinking
GO:0030234 enzyme regulator activity
Molecular Function
Definition (GO:0030234 GONUTS page)
Binds to and modulates the activity of an enzyme.

but I'm not sure if this is correct if it has only been shown to affect stability? it seems more like a "scaffold" and we don't have such a term (it is conflated with adaptor...I have issue with this https://docs.google.com/document/d/1Qakmsk19Sr4H_2cDpzMU0bi8duD7Rbye5aJ_Rne-7ZE/edit?usp=sharing
because not all scaffold proteins are adaptors

GO:0060090 molecular adaptor activity
Has related synonyms
protein complex scaffold activity
And
protein-containing complex scaffold activity

but this could be an example of a scaffold that isn't an adaptor.

@pgaudet what do you think?

[marcfeuermann]

I would indeed rather use GO:0060090 molecular adaptor activity.
At the PAINT level, annotation has been removed.
Feel free to further discuss or close this ticket.

[ValWood]

The problem with adaptor is that it implies a connection of A to B, via C and that does not seem to be the case here.
This is an ontology issue though...

[ValWood]

Although quite a few of these so called regulatory subunits are actually membrane adaptors for the catalytic subunt... I will see if I can find info about this for this one...

[ValWood]

still not clear from the 2 most recent papers I could find
https://pubmed.ncbi.nlm.nih.gov/35420475/ Leishmania donovani Ortholog 2022
https://pubmed.ncbi.nlm.nih.gov/34875117/ T. brucei 2022

[edwong57]

Yeah, I'm kind of getting hung up on the definition of 'molecular adaptor activity' stating "The binding activity of a molecule that brings together two or more molecules..." In these cases, that doesn't seem to be happening.

[ValWood]

Perhaps enzyme regulator is best?

This does not even seem to localize gpi14 to the membrane because GPI14 is a multimenbrane-spanning protein.
We know it is absolutely required for the activity, but we don't know the precise mechanism
@pgaudet is it OK to use enzyme regulator activity in these cases? It doesn't have catalytic activity, and it doesn't appear to be an adaptor - there isn't really any information on how it affects/contributes to the activity of gpi14