[Ontology-editors] [Transport] calcium ion transport question - necessarily directed?

[Peter D'Eustachio]

Coming in late on an issue that is tangential to the discussion about 
clacium that has happened since.

No, transport in its most general sense is not necessarily directed. 
So-called facilitated transporters make channels in otherwise impermeable 
membranes. The channels are more or less specific in the molecules that can 
traverse them - all hexoses, say, or only glucose. The direction of 
movement, however, is determined only by the concentrations of the 
transported molecule on the two sides of thr barrier, not by the 
transporter, so the same GLUT2 transporter that lets glucose into a 
hepatocyte when blood glucose levels are high and intracellular levels are 
low after a meal, also lets it out in the fasting state when intracellular 
levels are high due to de novo glucose synthesis inside the hepatocyte but 
low in the blood.

Peter D

----- Original Message ----- 
From: "Chris Mungall" <cjm at berkeleybop.org>
To: "Midori Harris" <midori at ebi.ac.uk>
Cc: "transport" <transport at genome.stanford.edu>; "Ontology Editors" 
<ontology-editors at genome.stanford.edu>
Sent: Thursday, February 05, 2009 12:24 PM
Subject: Re: [Transport] [Ontology-editors] calcium ion transport question


>  thought transport sensu GO meant *directed* movement.
>
> If I were to sneak into a zoo at night and unlock all the cages, would  I 
> be directing all the monkeys and lions into the surrounding city? I  guess 
> it depends on my intentions.
>
> I think it's similar here. There is a hidden notion of agency in the  GO 
> definition of transport. Of course, cells have no intentions, but  gene 
> products have evolved to carry out some role, so there is a form  of 
> agency here. Even so it may be easier if describe processes rather  than 
> ascribing goals.
>
> On Feb 5, 2009, at 4:00 AM, Midori Harris wrote:
>
>> just re-sending with a subject line ...
>>
>> On Thu, 5 Feb 2009, Midori Harris wrote:
>>
>>> Hi,
>>>
>>> Is anyone aware of any reason why 'release of sequestered calcium  ion 
>>> into cytosol' (GO:0051209) has no relationship to 'calcium ion 
>>> transport' (GO:0006816)? If not, I think it would make sense to add.
>>>
>>> This came up as part of SF 2560505:
>>>
>>> https://sourceforge.net/tracker/index.php?func=detail&aid=2560505&group_id=36855&atid=440764
>>>
>>> Thanks,
>>> Midori
>>> _______________________________________________
>>> Transport mailing list
>>> Transport at geneontology.org
>>> http://fafner.stanford.edu/mailman/listinfo/transport
>>>
>> _______________________________________________
>> Ontology-editors mailing list
>> Ontology-editors at geneontology.org
>> http://fafner.stanford.edu/mailman/listinfo/ontology-editors
>>
>
> _______________________________________________
> Transport mailing list
> Transport at geneontology.org
> http://fafner.stanford.edu/mailman/listinfo/transport
>