exocyst localization GO:0051601

[ValWood]

This term appears to be used occasionally to describe

vesicle tethering involved in exocytosis (i.e exocyst subunits)

See for example S.c EXO70 http://www.yeastgenome.org/locus/YJL085W/overview#go

pombe sec3 http://preview.pombase.org/gene/SPAC17G8.12

but
vesicle tethering involved in exocytosis is not related to exocyst localization GO:0051601

(I wonder if exocyst localization is even required?)

[ValWood]

9 EXP annotations http://www.ebi.ac.uk/QuickGO-Old/GTerm?id=GO:0051601#term=annotation

6 SGD 2 dictybase 2 Flybase 1 PomBase

All pombe and SGD are exocyts complex, tethering would be better?

The fly and dicty look like they might be "regulators of exocytosis" more generally

[vanaukenk]

@ValWood Looking at some of the references that have been used for the 'exocyst localization' annotations, I am wondering if some of the annotations were made with the idea of capturing the effects that loss of specific subunits of the exocyst has on polarized localization of the complex. At least in one case, Sec6p, it looked like the complex still assembled but polarized localization didn't occur.

I don't know how well understood the processes of exocyst assembly and localization are and whether it's possible to tease out what subunits might actually have an active role in localization vs whether loss of specific subunits just results in complex destabilization and subsequent loss of proper localization.

We could ask curators to review their annotations with this in mind. What do you think?

[ValWood]

"The tethering of the secretory vesicles prior to docking and fusion with the plasma membrane is mediated by the exocyst, a phylogenetically conserved and stable octameric protein complex (4,5). The two exocyst members Sec3 and Exo70 interact with phosphatidylinositol (4,5)-bisphosphate at the plasma membrane and assemble the rest of the exocyst complex, which is trafficked to the cell surface on vesicles in an actin-dependent manner (6-10)."

from intro of PMID:28765280

A schematic (googled, not from the paper)

So, since the sec3/Exo70 are a necessary part of the octomeric complex, the exocyst does not exist until after the tethering step.... exocyst localization therefore seems to be a different way of interpreting the "tethering" step. I don't think I would have called this localization, because there is no mechanism (attachment) step of the extant complex. It is created in the correct place by the "tethering" step.

GO:0090522 - vesicle tethering involved in exocytosis this might be better if worded "exoxyst-mediated vesicle tethering", and the def could be tweaked to mention exocyst (it's a very generic vesicle tethering definition)..... This term is also very under-annotated.

and if the localization step is required this could then be placed under "vesicle localization" and "exocyst localization"

[vanaukenk]

@ValWood How would you like to proceed with this one? This sounds like an annotation review is needed. Should we create a ticket there and link to this one?

[ValWood]

10 EXP annotation Action obsolete (with children) and recommend "exocyst tethering" or other suitable term