Gene expression ≠ protein accumulation

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Gene expression ≠ protein accumulation

I was remined lately that people forget that gene expression does not equal protein accumulation. And also that protein accumulated is not equal to protein that is actual able to do what it is made for. So here an explaination about gene expression, protein accumulation, why are they not the same, and why protein accumulation is not telling anything about functionality of the protein.

Gene expression

As I explained to my mum last night, you can think about it like this: when playing with LEGO, if you are making one type of car over and over again you can measure how fast you assemble that car. This measurement of assembly we call expression, so in this case it is LEGO-car expression we measure, for the expression of genes it is called gene expression.

Protein accumulation

Expression is however is telling you nothing about the number of cars of that type of car are actually there. That is not only dependent on the speed of car assembly (LEGO-car expression), but also on the speed of car disassembly. If assembly and disassembly are in balance it does not matter if the assembly speed (LEGO-car expression) is high or low because the total number available cars does not change. The total number of available we call accumulation, for our LEGO-cars it is LEGO-car accumulation, when we talk about the total number of available proteins it is protein accumulation.

Protein functionality

This explains how protein accumulation is dependent on more than just gene expression. In turn protein functionality is dependent on more than just protein accumulation. It is also dependent on something called posttranscriptional modifications. Back to our cars. If you have 5 vans that you use to deliver goods, but three are stuck at the petrol station waiting for fuel, then effectively you have only 2 vans that are able to go on their delivery rounds. In this example you can see being stuck at a petrol station as a posttranscriptional modification that takes away the functionality of the protein (3 vans are not functional) without changing to overall car accumulation (there are still 5 vans). The simple measure of supplying fuel (posttranscriptional modification) will increase the number of functional proteins without changing the overall number of vans (car accumulation).

Hopefully this will help you remember that gene expression does not equal protein accumulation and that protein functionality is dependent on more that just protein accumulation. No just remember, protein does not equal car.