Correlation of mRNA and protein

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sitara
sitara's picture
Correlation of mRNA and protein

 Hi
I like to know whether mRNA and Protein expression are always correlating. During time point studies, at 3 different time points, the first and last points of mrna expression are correlating with the protein in immunohistochemistry. but at the 2nd time point, the mrna is low but protein is the same

Is it the feed back effect due to retaining the proteins without degradation so that the mrna is downregulated. Are there any other reasons?

Thanks a lot

Sitara

Chin Fen Teo
Chin Fen Teo's picture
 Hi sitara,

 Hi sitara,

The levels of mRNA and protein do not necessary to go hand-in-hand. It can go through a feed back mechanism per your postulation or via other (more complicated) regulatory networks.  

If the protein level stays the same, one question to ask it that, how long the protein half-life is?

In the scenario that you described, I think you may want to look into (1) mRNA transcript level (2) mRNA stability (3) protein half-life, and see what the data tells you.

Good luck.

Jason King
Jason King's picture
 RNA is less stable than most

 RNA is less stable than most proteins so it could be that in that 1 sample something happened during the RNA and cDZnA prep that impacted on the qPCR (I assume this is how you quantified the RNA).

The sensitivity of qPCR is also much higher than that of immunofluorescence, especially if the levels of expression are quite high so you might have less protein but be unable to see the difference.

you might get a better protein quantification by doing a western blot and titrating back the amount of extract added.