"protein quantity" is correct and it can be used in written English.
It is most commonly used in scientific or medical contexts, for example: "The protein quantity of the patient's blood sample was well within the normal range."
Caution is needed when extrapolating our results to protein quantity, as our results represent RNA expression levels which is still several steps removed from the final protein product45.
Protein concentration was quantified by BCA assay and the levels of frataxin protein were measured by lateral flow immunoassay with the Frataxin Protein Quantity Dipstick Assay Kit (MitoSciences, Eugene, OR, USA) according to the manufacturer's instructions47.
To determine the levels of human frataxin expression in the FAST-1 overexpressing cells, frataxin protein expression levels were measured by lateral flow immunoassay with the Frataxin Protein Quantity Dipstick assay kit.
Protein quantity in a lysate was measured by the Bradford method [38].
Notably, relative changes of protein quantity can be elucidated with the method applied here.
The color code represents the log2 mean fold change (log2 FC) of protein quantity in one pathway.
We presume that the increased amount of cellular glucose uptake is proportional to the elevated production of proteins, thus increasing absolute protein quantity but leaving relative quantity unchanged.
Besides, determination of protein quantity in biological liquids is of great importance in biology and medicine and fluorescent probes are successfully applied for this approach [21].
Diseases like cancer can manifest themselves through changes in protein abundance, and microRNAs (miRNAs) play a key role in the modulation of protein quantity.
Significant changes in protein quantity were defined by exceeding a threshold of more than 1.5 fold change (FC) in combination with a p-value < 0.05 (Student's t-test).
There was a positive correlation between protein quantity and enzyme activity (R = 0.72; Figure 2C).
