Amino acid residue specific stable isotope labeling for quantitative proteomics

Area of Science:

• Proteomics
• Mass Spectrometry
• Biochemistry

Background:

• Stable isotope labeling (SIL) techniques enhance protein quantitation accuracy in mass spectrometry (MS).
• Accurate protein abundance measurement is crucial for understanding cellular processes and disease mechanisms.

Purpose of the Study:

• To extend a residue-specific SIL approach for accurate quantitation of protein abundances across different cell populations.
• To demonstrate the applicability of this SIL strategy in analyzing differential protein expression in yeast and human cells.

Main Methods:

• Developed a mass-tagging strategy for residue-specific incorporation of stable isotope-tagged amino acids during cell growth.
• Utilized the linear correlation between isotopic peak areas and cell mixing ratios for quantitation.
• Applied the method to analyze the yeast proteome in response to the Zap1 transcription factor and to study radiation response in human fibroblasts.

Main Results:

• Successfully quantified differential protein expression in wild-type versus zap1delta yeast cells, identifying Methionine synthase (Met6) upregulation.
• Determined a two-fold increase in a novel protein's expression in human fibroblasts post-radiation.
• Demonstrated the method's general applicability with various amino acid precursors.

Conclusions:

• The residue-specific SIL strategy provides accurate quantitation of protein relative abundances across diverse cell types and conditions.
• This method is a versatile tool for proteomic studies, including transcription factor effects and cellular responses to stimuli like radiation.
• The approach offers a robust platform for advancing quantitative proteomics and biomarker discovery.