Ubiquitin is a small (~8.5KDa) regulatory protein that has been found in almost all cells. It directs proteins to recycling and other functions.
Ubiquitination is one among the post-translational modifications (PTMs) where ubiquitin is attached to a substrate protein.
Steps in Ubiquitination #
- Activation - Ubiquitin-activating enzymes (E1)
- Conjugation - Ubiquitin-conjugating enzymes (E2)
- Ligation - Ubiquitin ligases (E3)
ubiquitination (유비퀴틴화) plays a vital role in regulating wide range of biological processes, such as signal transduction, cell division, apoptosis, and immune response. Ubiquitination is also named "lysine ubiquitination" because it occurs when an ubiquitin is covalently attached to lysine (K) residues of targeting proteins (단백질). Experimental approaches for identifying these lysine sites are often expensive, labor-intensive and time-consuming, partly due to the dynamics and reversibility of ubiquitination. With the avalanche of protein sequences generated in the postgenomic age, in silico prediction is potentially a useful strategy for whole proteome annotation. A number of bioinformatics approaches and tools (webservers and standalone software’s) have recently been developed for predicting protein ubiquitination sites. Only one mammalian ubiquitination site database is reported so far (mUbiSiDa).