Protein synthesis as a function of protein content in exponentially growing NHIK 3025 cells studied by flow cytometry and cell sorting

Methods of cell preparation and quantitative flow cytometric cell sorting were developed for precise measurements of the incorporated radioactivity in cells labelled with ¹⁴C]-valine and fractionated as a function of their fluorescence intensity after staining with fluorescein-iso-thiocyanate (FITC). FITC fluorescence intensity of exponentially growing NHIK 3025 cells was found to be directly proportional to cellular protein content as measured by saturation-labelling with ¹⁴C]-valine. Protein synthesis as measured by ¹⁴C incorporation after pulse-labelling was found to increase nearly proportionally with cellular protein content. The deviations from proportionality were not greater than 6%, but yet found to be significant since the measurement error corresponded to only 2% standard deviation.