Characterization of the human urine proteome by preparative electrophoresis in combination with 2-DE

The protein components of urine are useful indicators of renal function and human health in general. Urine samples are easily attainable making them ideal substrates for biomarker research. Analysis of the urine proteome however, has been hindered by the great variability of the urine specimens, and the presence of various proteins in low abundance or modified forms. To alleviate some of these problems urine samples from five different individuals were pooled, concentrated and the proteome characterized by a combination of preparative electrophoresis and 2-DE, followed by PMF. A total of 778 protein spots corresponding to 141 different gene products were identified. In comparison, 171 spots corresponding to 44 unique proteins were identified in the unfractionated starting material. Among the proteins identified from the preparative electrophoresis were many of low abundance such as proteins involved in signal transduction. Furthermore, the median molecular mass of the identified proteins from the preparative electrophoresis was significantly lower in comparison to the proteins identified from the unfractionated starting material (39 886 Da versus 71 317 Da, respectively). Concluding, application of this methodology provides a coherent analysis of the urine proteome and contributes to the generation of the urine protein map in health and disease.