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Sodium Orthovanadate kinetics in media incubations - (Oct/11/2007 )

Our current protocol involves a one minute, five minute, ten minute, and one hour incubation of cells with treatment and control media both supplemented with sodium orthovanadate. We are repeatedly seeing a strong phosphorlyation signal in our one minute sample and one hour sample. However the five minute time point is incredibly faint and the ten minute is non-existent.
How is this possible if sodium orthovanadate is preventing phosphatase activity?
Does the activity of sodium orthovanadate wear off after a few minutes at 37C?
Any help from anyone with knowledge about sodium orthovanadate would be great.

-camlogan-

QUOTE (camlogan @ Oct 11 2007, 09:42 AM)
Our current protocol involves a one minute, five minute, ten minute, and one hour incubation of cells with treatment and control media both supplemented with sodium orthovanadate. We are repeatedly seeing a strong phosphorlyation signal in our one minute sample and one hour sample. However the five minute time point is incredibly faint and the ten minute is non-existent.
How is this possible if sodium orthovanadate is preventing phosphatase activity?
Does the activity of sodium orthovanadate wear off after a few minutes at 37C?
Any help from anyone with knowledge about sodium orthovanadate would be great.


what is the reason to use ortho-vanadate for cells? is it to block phosphate transporters?

-The Bearer-

I should have been more specific. We are lysing the cells and measuring phosphorylation of an ITAM, our lysis buffer also contains sodium orthovanadate.

-camlogan-

QUOTE (camlogan @ Oct 12 2007, 02:14 PM)
I should have been more specific. We are lysing the cells and measuring phosphorylation of an ITAM, our lysis buffer also contains sodium orthovanadate.


so you use it as phosphatase inhibitors; I think, but may be wrong, that ortho-vanadate is more specific to phospho-Y phosphatases; it appears to be sterically similar to phosphoryls and blocks the catalytic site of phosphatases;

commonly used in lysis buffers to save phosphorylations...

-The Bearer-