This study evaluates the effectiveness of two-dimensional gel electrophoresis (2DE) combined with mass spectrometry (MS) for proteome analysis. The research focuses on the ability of this technique to detect and identify proteins in yeast, particularly low-abundance proteins. The study used a narrow pH range (4.9–5.7) 2D gel to separate 0.5 mg of total soluble yeast protein. Over 1,500 protein spots were visualized by silver staining, and 50 spots were analyzed by MS. However, proteins from genes with codon bias values of <0.1 (lower abundance proteins) were not detected, even though more than half of all yeast genes fall into this category. This suggests that the 2DE-MS approach is limited in its ability to detect medium to low abundance proteins. The study also examined the detection of low abundance proteins by increasing the starting protein load. When 50 mg of yeast protein was separated by SDS-PAGE and analyzed by strong cation exchange chromatography followed by LC-MS/MS, 193 proteins were detected, including 60 proteins from genes with codon bias values of <0.1. This indicates that larger starting amounts of protein are necessary to detect low abundance proteins. The study highlights the limitations of 2DE-MS for proteome analysis, particularly in detecting low abundance proteins. It also emphasizes the need for improved techniques that allow for larger starting amounts of protein to provide sufficient quantities for MS analysis. The results suggest that while 2DE-MS is a powerful tool for proteome analysis, it is not suitable for comprehensive detection of all proteins in a sample. The study concludes that the current proteome technology, without sample preenrichment, is not suitable for the global detection of proteins expressed by the cell.This study evaluates the effectiveness of two-dimensional gel electrophoresis (2DE) combined with mass spectrometry (MS) for proteome analysis. The research focuses on the ability of this technique to detect and identify proteins in yeast, particularly low-abundance proteins. The study used a narrow pH range (4.9–5.7) 2D gel to separate 0.5 mg of total soluble yeast protein. Over 1,500 protein spots were visualized by silver staining, and 50 spots were analyzed by MS. However, proteins from genes with codon bias values of <0.1 (lower abundance proteins) were not detected, even though more than half of all yeast genes fall into this category. This suggests that the 2DE-MS approach is limited in its ability to detect medium to low abundance proteins. The study also examined the detection of low abundance proteins by increasing the starting protein load. When 50 mg of yeast protein was separated by SDS-PAGE and analyzed by strong cation exchange chromatography followed by LC-MS/MS, 193 proteins were detected, including 60 proteins from genes with codon bias values of <0.1. This indicates that larger starting amounts of protein are necessary to detect low abundance proteins. The study highlights the limitations of 2DE-MS for proteome analysis, particularly in detecting low abundance proteins. It also emphasizes the need for improved techniques that allow for larger starting amounts of protein to provide sufficient quantities for MS analysis. The results suggest that while 2DE-MS is a powerful tool for proteome analysis, it is not suitable for comprehensive detection of all proteins in a sample. The study concludes that the current proteome technology, without sample preenrichment, is not suitable for the global detection of proteins expressed by the cell.