Toward a comprehensive characterization of the XXXX proteome.

@entity9220 @entity10393 @entity18078 @entity58149 @entity1778 @entity105 @entity669 @entity34051 @entity26112
@entity669 phosphorylation (pTyr) regulates important cell functions and plays a key role in @entity105 . The purpose of this study was to perform a comprehensive study of the @entity10393 proteome. Immunoaffinity enriched pTyr proteins and peptides from K562 @entity1778 cells were analyzed with high-resolving liquid chromatography mass spectrometry. Two different antibodies selective for the pTyr modification were used in repeated enrichments to identify as many pTyr peptides as possible. Stringent verification of putative pTyr sites was performed to assure high reliability in the subsequent biological interpretation of the data. Identified pTyr proteins were subjected to pathway analysis by using different analytical tools. In total, 294 pTyr peptides belonging to 217 pTyr proteins were identified, 15 of which had not previously been reported to be modified by pTyr. The pTyr proteins were clustered in six major groups based on the biological functions "cellular signaling", "cell motility and shape", "cell cycle process", "transport", "RNA processing" and "protein processing". The pTyr proteins were mainly positioned in the following cellular compartments: cytoplasm, cytoskeleton, nucleus and ribonucleoprotein complexes. An interesting finding was that many proteins were related to RNA processing and were found to be heterogeneous nuclear ribonucleoproteins. Also, more than half of the novel pTyr proteins were localized to the nucleus, of which three ( @entity58149 , @entity9220 and @entity18078 ) were classified as transcription factors and two ( @entity34051 and @entity26112 ) are associated with cell division control.
