Characterization of the human plasma phosphoproteome using linear ion trap mass spectrometry and multiple search engines.
Major plasma protein families play different roles in blood physiology and hemostasis and in immunodefense. Other proteins in plasma can be involved in signaling as chemical messengers or constitute biological markers of the status of distant tissues. In this respect, the plasma phosphoproteome holds potentially relevant information on the mechanisms modulating these processes through the regulation of protein activity. In this work we describe for the first time a collection of phosphopeptides identified in human plasma using immunoaffinity separation of the seven major serum protein families from other plasma proteins, SCX fractionation, and TiO(2) purification prior to LC-MS/MS analysis. One-hundred and twenty-seven phosphosites in 138 phosphopeptides mapping 70 phosphoproteins were identified with FDR < 1%. A high-confidence collection of phosphosites was obtained using a combined search with the OMSSA, SEQUEST, and Phenyx search engines.
Carrascal
Montserrat
M
LP-CSIC/UAB, IIBB-CSIC, IDIBAPS, Rosellón 161, 7a Planta, 08036 Barcelona, Spain.
Gay
Marina
M
Ovelleiro
David
D
Casas
Vanessa
V
Gelpí
Emilio
E
Abian
Joaquin
J
D000595:Amino Acid Sequence; D002846:Chromatography, Affinity; D006801:Humans; D016247:Information Storage and Retrieval; D013058:Mass Spectrometry / Q000379:methods*; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000097:blood* / Q000737:chemistry; D020543:Proteome; D053719:Tandem Mass Spectrometry
D010750:Phosphoproteins; D020543:Proteome