This database of urinary exosome proteins is based on published and unpublished protein mass spectrometry data from the NHLBI Laboratory of Kidney and Electrolyte Metabolism. All data are from urinary exosomes isolated from healthy human volunteers. The figure on the right illustrates the mechanism of exosome formation and excretion.
In the first step of the process, apical membrane proteins undergo endocytosis. In the second step, the endosome is targeted to the multivesicular body (MVB). The signal that marks plasma membrane proteins for incorporation into MVB is mono-ubiquitination. In the third step, the endosome fuses with the MVB. Consequently, the apical plasma membrane proteins are segregated in the MVB outer membranes and internalized by membrane invagination. Finally, the outer membrane of the MVB fuses with the apical plasma membrane releasing its internal vesicles, called ‘exosomes’, in the urinary space. Exosomes contain both membrane and cytosolic proteins.
This current database contains protein identification of human urinary exosomes using two different mass spectrometer analyzers. The LCQ mass analyzer was used for technique # 1 and the LTQ mass analyzer was used for technique # 2.
- Pisitkun T, Shen RF, Knepper MA. Identification and proteomic profiling of exosomes in human urine. Proc Natl Acad Sci U S A. 2004 Sep 7;101(36):13368-73.
- Gonzales PA, Pisitkun T, Hoffert JD, Tchapyjnikov D, Star RA, Kleta R, Wang NS, Knepper MA. Large-scale Proteomics and Phosphoproteomics of Human Urinary Exosomes. J Am Soc Nephrol. in press