The hUbiquitome Blast is useful for retrieving possible ubiquitinated lysine sites of interesting proteins. different substrate proteins and 17 deubiquitination enzyme terms. The biological functions of substrates from different kinds of E3s were analyzed using the collected data. The findings show that substrates ubiquitinated by RING (Really Interesting New Gene) E3s are enriched most in apoptosis-related processes, whereas substrates ubiquitinated by other E3s are enriched in gene expression-associated processes. An analysis of the data demonstrates the biological process preferences of the different kinds of E3s. hUbiquitome is the first database to systematically collect experimentally validated ubiquitinated proteins and related ubiquitination cascade enzymes which might be helpful in the field of ubiquitination-modification research. Database URL:http://202.38.126.151/hmdd/hubi/ == Introduction == Ubiquitination is an important type of post-translational modification in which an isopeptide bond is formed between the C-terminus of ubiquitin and a lysine residue from either a substrate or another ubiquitin molecule (1). In addition to its initial role in protein degradation (2), ubiquitination regulates other cellular processes, including transcription, cell cycle, DNA repair, apoptosis and receptor endocytosis (3). Thus, aberrations of ubiquitinproteasome system function in all the above-mentioned processes have been implicated in the pathogenesis of human diseases, ranging from inflammatory, neurodegenerative muscle-wasting, to various forms of malignancies (4,5). A few resources of ubiquitination data are available. Ubiprot is the first database on ubiquitination (6), which focuses on the properties of ubiquitinated proteinsper se, with data from different species combined. The data in Ubiprot are mainly sourced from several high-throughput studies, and do not include information of ubiquitination cascade enzymes. The other ubiquitination database is a yeast database [Saccharomyces cerevisiae Ubiquitination Database (SCUD)] focusing on ubiquitination cascades (7). SCUD has collected almost all known enzymes involved in the ubiquitination process of yeast and has grouped them into affordable classes. E3Miner is a text-mining tool for literature search (8), and appears to replace labor-intense manual curation with machine learning approach. Although E3Miner contains many useful E3-centered information, obtaining high accuracy in the text-mining method is hard. Ubiquitination is a conserved biological process from yeasts to humans (1,912). Understanding of the human ubiquitination system has gradually become clearer as more enzymes and ubiquitinated proteins have been discovered (1315). However, no database Rucaparib demonstrating those of the human ubiquitination system exists. hUbiquitome is the first and largest searchable collection of human ubiquitination proteins and cascades. hUbiquitome was constructed based on published papers in PubMed, and all the ubiquitination proteins and cascades were experimentally validated. hUbiquitome provides a user-friendly interface through which information can be easily retrieved, including E1, E2 and E3 substrates, deubiquitination enzymes (DUBs) and the relationship among these elements. Ubiquitin lysine sites or sequences are provided if they were identified in the reference papers. If some E3 functions are in the form of complexes, a complex name would be provided. hUbiquitome aims Rucaparib to provide as many precise information as confirmed by experiments in the ubiquitination cascades. == Database construction == The ubiquitination cascade data documented in the current version, hUbiquitome 1.1.1, were collected manually by searching the PubMed database for primary research articles published or e-published up to the time of the present study with a list of keywords (e1 ubiquitin OR e2 ubiquitin-conjugating enzyme OR e3 ubiquitin ligases Limits: Humans). Full articles and supplementary data were examined. When appropriate, references were checked for additional materials. Studies that explained experimentally identified associations between E2 and E3 and E3 Hsh155 and Substrate were included. Only papers showing adequate experimental evidence of substrate ubiquitination by recognized Rucaparib E3s were selected. Experimental evidence includesin vitroreaction of E3 and substrate, immunoblot with ubiquitin antibody, autoradiogram of isotope-labeled ubiquitin, tag-labeled ubiquitin detection, substrate degradation by proteome, substrate stability detection and so on. Additional information, such as E3 complex components and ubiquitinated sites and sequences, are important features of hUbiquitome. Another part of the ubiquitination system is the deubiquitination process (1619). DUBs are involved in multiple cellular processes much like ubiquitinating enzymes (UBs). However, studies on DUBs lag behind that of UBs. Seventeen terms of DUBs with recognized substrates.