#10998 NTR - GO:0048791 calcium ion-dependent exocytosis of neurotransmitter - child

[Paul Denny]

GO:0048791 calcium ion-dependent exocytosis of neurotransmitter
Two new BP child terms to this term, based on PMID:7954835 and PMID:7809151

There are two distinct types of calcium ion-dependent release (exocytosis) of neurotransmitter - one is called fast, "synchronous" release and depends on a molecular Ca2+ sensor with lower Ca2+ affinity that mediates >>80% of the release of transmitter and the other is slower, "asynchronous" reflecting a higher Ca2+-affinity mechanism and is responsible for <<20 % of the release.

I'd like to request a term for each of these (fast and slow).
I would use one of the terms to annotate synaptotagmin 1 (P46096) in PMID:7954835 and the other will be used in future when molecular underpinning of these processes is clarified.

[David Osumi-Sutherland]

Progress: I have provisionally added two terms:

label "slow, calcium ion-dependent exocytosis of neurotransmitter"
definition "The slow, second phase of calcium ion-induced neurotransmitter release, via exocytosis, into the synaptic cleft. This depends on high affinity calcium sensors and decays slowly, typically with a decay constant of over 100ms. The underlying molecular mechanisms of this process are distinct from those of the earlier, fast phase of release."
is_a: 'calcium ion-dependent exocytosis of neurotransmitter'

label "fast, calcium ion-dependent exocytosis of neurotransmitter"
definition "The fast, intial phase of calcium ion-induced neurotransmitter release, via exocytosis, into the synaptic cleft. This depends on low affinity calcium sensors and typically begins a fraction of a millisecond after Ca2+ influx, and decays rapidly (1-10ms) with a decay constant of around 5-10ms. The underlying molecular mechanisms of this process are distinct from those of the later, slow phase of release."
has_exact_synonym "synchronous, calcium ion-dependent exocytosis of neurotransmitter"
is_a: 'calcium ion-dependent exocytosis of neurotransmitter'

These are not yet public.

Having added these, I noticed two existing terms which are probably equivalent.

• synchronous neurotransmitter secretion
• asynchronous neurotransmitter secretion

These probably correspond to the terms you've requested, but are defined quite differently. Now looking in to whether merge is justified and if so, what names should win.

[Paul Denny]

HI David,
I tried looking at the contents of the links:
synchronous neurotransmitter secretion ( http://purl.obolibrary.org/obo/GO_0071911 )
asynchronous neurotransmitter secretion ( http://purl.obolibrary.org/obo/GO_0071912 )
But unfortunately couldn't access them.
What else is needed before these new terms can be used?

[David Osumi-Sutherland]

HI Paul,

These are just GO term links. Unfortunately the PURL server I linked to seems to be playing up (yet again). You can find these terms on QuickGO. The new terms should also be public now too. I'll look in to merging them later this week. If I do merge, you shouldn't need to worry about your annotations (they'll just migrate). If I don't I'll post more on this ticket to let you know what I've done.

Cheers,
David

[David Osumi-Sutherland]

Notes on related stuff to clean up (should be moved to a new ticket - parking here for convenience):

exocytosis and secretion are separate hierarchies. No way to relate secretion via exocytosis to exocytosis. Should hierarchies be merged? If not what relationship should they have? Here are some examples relevant to the terms requested in this ticket.

exocytosis
. calcium ion-dependent exocytosis
. synaptic vesicle exocytosis
. regulated secretory pathway: "A process of exocytosis in which soluble proteins and other substances are initially stored in secretory vesicles for later release. It is found mainly in cells that are specialized for secreting products such as hormones, neurotransmitters, or digestive enzymes rapidlon demand."
. . neurotransmitter secretory pathway: ""

secretion
. neurotransmitter secretion (formerly neurotransmitter release)
. . calcium-ion dependent exocytosis of neurotransmitterB

neurotransmitter transport
. neurotransmitter secretion

[Paul Denny]

Hi david - how is tidying up / merging of these progressing?
Cheers

[David Osumi-Sutherland]

From discussion at the Synapse Jamboree meeting, it seems that these terms should be merged. However, I'm having trouble reconciling the definitions. Luckily, the synapse project should allow me to get expert input into defining the merged terms. This will happen in the new year. Whichever terms win from the merge, you annotations should move across seamlessly, so no need to keep this ticket open I think. I'll close this ticket and open a new one for discussing the merge.