4. Phosphoproteome: Sample
Preparation
Chia-Wei Hu and Hsueh-Fen Juan∗
Institute of Molecular and Cellular Biology,
National Taiwan University, Taipei, Taiwan
∗[email protected]- Introduction
Protein phosphorylation is one of the most important post-translational
modifications in cells. It plays a crucial role in various biological processes
including cell cycle, cell signaling, and metabolism. In eukaryote, it is
believed that phosphorylation is involved in at least 40% of proteins.^1
Kinases and phosphatase are the two major enzymes that control the
reversible phosphorylation/dephosphorylation mechanism using adenosine
triphosphate (ATP) as its phosphate donor. In signal transduction, phospho-
rylation mediates signal attenuation and termination, whereas an aberrant
regulation of protein phosphorylation often results in uncontrolled cell
signaling, leading to a variety of diseases.2,3Therefore, the systematic study
of phosphorylation events is an important determinant for understanding
the regulation of cell physiology.
The efficient enrichment of phosphopeptides and high-resolution analyzer
are highly required for the low presence of phosphorylated proteins in cell.
Many strategies have been developed recently to selectively enrich phos-
phopeptides, including immobilized metal affinity chromatography (IMAC),
titanium dioxide (TiO 2 ) enrichment, strong cation exchange chromatog-
raphy, and antibody-based enrichment.3,4Among these approaches, TiO 2
is one of the most widely used methods in phosphoproteomic analysis.
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