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Summary: The uniqueness of a measured molecular mass or peptide sequence plays a very important role in the fields of protein identification and peptide/protein-biomarker investigation. We present a publicly available web application that offers information concerning the uniqueness of one or more molecular masses and one or more peptide sequences in the human proteome. When a sequence is found to be unique in humans, the application is able to search across all species querying whether this sequence is unique, not only in humans but also in other species found in the Swiss-Prot Database. The application is also able to search for unique protein fragments derived computationally from enzymatic digestion driven by certain enzymes. Furthermore, the application can list all the unique masses and peptides of a given protein. Through this application, researchers are able to find unique tags, either on a molecular mass level or on a sequence level. These unique tags are remarkably important in research related to protein identification or biomarker discovery and measurements. Availability: UniMaP web-application is available at http://bioserver -1.bioacademy.gr/Bioserver/UniMaP/ Contact: gspyrou@bioacademy.gr Supplementary information: Supplementary data are available at Bioinformatics online. The precise identification of peptide sequences and proteins is of great significance in proteomics. Specifically, in mass spectrometry, isolated proteins or protein mixtures are digested by enzymes into peptides. These peptides are then ionized by different techniques (TOF, ESI) and detected producing mass spectra that are computationally analyzed. The peptides identified with statistical significance are used for protein identification (Liebler, 2002; Marcotte, 2007). In proteomics technology of selected reaction monitoring (SRM) or multiple reaction monitoring (MRM), a predefined precursor ion and one of its fragments are selected by a filtering device and monitored over time for precise quantification (Lange et al., 2008). The determination of unique characteristics for a protein is profoundly interesting in the application of the new concepts of

We report the establishment of two novel clear cell sarcoma (CCS) cell lines (soft tissue melanoma) from a patient and the production of the corresponding xenografts after xenotransplantation of those cells to NOD/SCID mice. As no comprehensive study on the relevant proteomes of this type of cancer has been reported to date, proteomics technologies were applied in a first attempt to analyze the proteins of the two cell lines and their corresponding primary xenografts. Total protein extracts were separated by two dimensional gel electrophoresis (2-DE) and analysed by MALDI-MS and MALDI-MS-MS following in-gel digestion with trypsin. Protein identification was carried out by peptide mass fingerprint (PMF) and post source decay (PSD), respectively. Comparative analysis revealed that 124 proteins were common between the cell lines and the xenografts; 249 proteins were found to be expressed only in the proteome of the cell lines, while 178 proteins were expressed only in the proteome of xenografts. Our results demonstrated that both cell lines and xenografts were positive for vimentin and S100 reported as markers for CCS. After functional analysis, 27 different protein groups were identified in the analysed proteomes, including apoptosis-related proteins, oncogenes and several proteins closely related to TP-53 and NF-kappa B pathways. Furthermore, the proteins nestin, stem cell growth factor CLC11 and mdr-1, closely related to malignant-melanoma-initiating cells, were found to be expressed in both the cell lines and their corresponding xenografts. Since there are no data concerning protein expression in CCS, this study may contribute to the understanding of the molecular basis of the disease, while the cell lines as well as the developed xenografts may be used as tools for the development of new therapeutic strategies to tackle this rare but fatal malignancy.

The human osteosarcoma U2OS cell line is one of the first generated cell lines and is used in various areas of biomedical research. Knowledge of its protein expression is limited and no comprehensive study on the proteome of this cell line has been reported to date. Proteomics technology was used in order to analyse the proteins of the U2OS cell line. Total protein extracts were separated by two-dimensional gel electrophoresis (2-DE) and analysed by matrix-assisted laser desorption ionisation-mass spectrometry (MALDI-MS) and MALDI--MS-MS following in-gel digestion with trypsin and, finally, protein identification was carried out by peptide mass fingerprint (PMF) and post source decay (PSD), respectively. Approximately 3,000 spots were excised from two 2-DE gels and were analysed, resulting in the identification of 237 different gene products. The majority of the identified proteins were enzymes, regulatory proteins and RNA-associated proteins, while leukocyte markers and oncogenes were also present. Our findings include 11 protooncogenes (FKBP4, SRC8, PSD10, FUBP1, PARK7, NPM, PDIA1, OXRP, SET, TCTP and GRP75) related to the cancerous state of the U2OS cell line. The U2OS 2-DE database provides the basis for future protein studies.

Proteomic analysis combining two-dimentional electrophoresis (2DE) and mass spectrometry (MS) has the potential for a wide range of applications in biological and medical sciences, as protein screening in tissues obtained from healthy and diseased conditions can determine drug targets and diagnostic markers. Conventionally, amniotic fluid (AF) samples are routinely used for prenatal diagnosis of a wide range of fetal abnormalities. Proteomics have already been applied in the analysis of tissues from fetuses with Down's syndrome, in order to detect differences in their protein profile as compared to the normal profiles and to determine possible diagnostic tools. A detailed protein 2DE for the normal human AF has not been reported. In the present study, the 2D protein database of the normal human AF supernatant (AFS) was constructed. Ten AFS samples from women carrying normal fetuses were analysed by 2DE. A mean of 412 spots per gel were analyzed and protein identification was carried out by MALDI-MS and MALDI-MS-MS. A 2D protein map comprising of 136 different gene products was constructed. The majority of the identified proteins are regulatory proteins, enzymes, secreted proteins, carriers and immunoglobulins. Twelve hypothetical proteins were also included. The normal AFS proteome map is a valuable tool for the study of aberrant protein expression and the search for proteins as possible markers for the prediction of abnormal fetuses.