 Stable isotope labeling by amino acids in cell culture

Stable isotope labeling by amino acids in cell culture incorporates isotopically distinct amino acids into proteins during cell growth. Mixing differently labeled samples produces peptide pairs with predictable mass differences, enabling relative quantification by mass spectrometry.

The labels preserve closely related chemistry while changing mass. Interpretation requires adequate incorporation and awareness of amino-acid conversion or growth-related differences. The method compares labeled protein populations; it does not make every observed abundance change a direct change in protein synthesis rate.