Biochemists - phospholipids

darkenergy

In the phospholipase C pathway, phosphotidyl-inositol 4,5-bisphosphate is hydrolysed to form inositol 3,4,5-triphosphate and diacylglycerol. My question is, where does the extra phosphate group come from? :confused:

ATP or an equivalent perhaps

Reply 2

boltcarrier

darkenergy

In the phospholipase C pathway, phosphotidyl-inositol 4,5-bisphosphate is hydrolysed to form inositol 3,4,5-triphosphate and diacylglycerol. My question is, where does the extra phosphate group come from? :confused:

i dont actually know anything about this pathway, sounds like university level (which im not yet at), but usually if you have extra phosphates coming in, it might be from the hydrolysis of ATP>ADP? like the phosphorylation of glucose in respiration, which is nice because it also provides energy for the reaction

btw, are you at cambridge university?

Reply 3

OP

Revenged

ATP or an equivalent perhaps

Do you know the source?

boltcarrier

i dont actually know anything about this pathway, sounds like university level (which im not yet at), but usually if you have extra phosphates coming in, it might be from the hydrolysis of ATP>ADP? like the phosphorylation of glucose in respiration, which is nice because it also provides energy for the reaction

i don't think it's ATP because in the pathway cycle the diagram showed ATP is used to phosphorylate PIP2 to PIP3; but no ATP is mentioned in the hydrolysis of PIP2.

boltcarrier

btw, are you at cambridge university?

Yes, but no; i.e. it's holiday :p:

Reply 4

Revenged

darkenergy

Do you know the source?

Well I didn't have a clue about what you were talking about at first... but I googled

The link makes it clear... The G protein receptor phosphorlyates this compound using GTP splitting it up...

http://isoft.postech.ac.kr/Research/POSBIOTM/image/GPCR/PLC.jpg

Reply 5

OP

Thanks!

Actually I didn't realise this:
the G-protein has GTP bound to it and has intrinsic GTP-hydrolysing activity; maybe the phosphate formed is used by the phospholipase C to phosphorylate th e inositol?

Reply 6

Revenged

darkenergy

Thanks!

Actually I didn't realise this:
the G-protein has GTP bound to it and has intrinsic GTP-hydrolysing activity; maybe the phosphate formed is used by the phospholipase C to phosphorylate th e inositol?

I have absolutely no idea :cool:

Reply 7

OP

Come on, are all the biochemists still in the labs at this time!?

Reply 8

boltcarrier

Yes, but no; i.e. it's holiday :p:

oh yeah i forgot. ah well, a half decent guess for me anyway :smile:

OP

Indeed.

phosphotidyl-inositol 4,5-bisphosphate

This molecule actually contains three phosphate groups, not two...two of them implied by the 'bisphosphate' and the other one by 'phospho'. So that solves your problem :wink:

. Diagram of the molecule here:

http://las.perkinelmer.com/Content/Images/smallImages/net895.jpg

Reply 11

OP

Looking at the molecule it makes perfect sense now: inositol with 3 phosphates, and two bits which hopefully constitute the DAG!

Thanks a lot - rep coming. Just came back from the lab then? :rolleyes:

Reply 12

nikk