XPRESS

XPRESS performs quantitative identification and relative-abundance analysis of proteins using isotope-coded affinity tag (ICAT) labeling coupled to mass spectrometry, with emphasis on membrane and microsomal proteins.

Key Features:

• Isotope-Coded Affinity Tagging: Uses ICAT reagents to covalently label cysteine-containing proteins and supports comparative labeling strategies including cICAT, SILAC, and N-14/N-15 experiments for relative quantification.
• Multidimensional Chromatography and Mass Spectrometry: Supports isolation and high-resolution separation of tagged peptides by multidimensional chromatography and identification/quantification by automated tandem mass spectrometry.
• Computational Analysis: Integrates computational tools to process tandem mass spectrometry data for peptide/protein identification and calculation of relative abundances.
• Software Support: Includes software components to handle large-scale quantitative proteomic datasets and to enable downstream computational analysis of ICAT-labeled experiments.

Scientific Applications:

• Comparative quantitative proteomics: Enables differential protein-expression analysis between distinct biological states using labeled mass spectrometry data.
• Microsomal and membrane protein analysis: Applied to microsomal fractions from cells or tissues, with emphasis on challenging membrane proteins.
• Case study — HL-60 cells: Used to compare naïve and differentiated human myeloid leukemia (HL-60) cells, facilitating identification and quantification of 491 distinct proteins.

Methodology:

Computational analysis of automated tandem mass spectrometry data for peptide identification and relative-abundance quantification of ICAT-labeled samples.