It’s widely known that numerous of physiological and biochemical processes within cells are accomplished by protein. A tiny cell can contain millions of proteins which are translated and synthesized by ribosome.
However, after synthesis, these protein molecules often have to undergo post-translational modification, which has important biological significance. Ubiquitinylation is one type of post-translational modification. In other words, after “dressing up” by some “junior partners”, proteins were sent for “mission”. Its partners include: phosphate groups, ubiquitin molecule, acetyl, methyl glucoside chain and so on and different modifications occur at different amino acid residues. For instance, phosphorylation may occur on serine, threonine and tyrosine residues; Ubiquitinylation and Acetylation occurs mainly on the lysine residues, etc.
So, after all these modifications, what abilities has the protein increased?
Post-translational modification of proteins can control cell differentiation. Rip laboratory work found that ubiquitin ligase CUL3 protein and its specific substrate adapter proteins KBTBD8 in vertebrates is required in human and Xenopus neural crest specialization. Two proteins together, through a series of biochemical reactions, cell differentiation modified translation program can support specialization of neural crest cells.
Ubiquitinylation can also degrade various proteins in vivo, thus adjusting the signal transduction pathway. For example, when the auxin molecules are bound to the receptor in plant cells, the interaction between the receptor and the target proteins would be strengthened and the target protein is rapidly ubiquitinated , resulting in degradation of the target protein.
Post-translational modification of proteins can rapidly degrade proteins that are not needed in a cell. For example, misfolded proteins can be ubiquitinated to be degraded by the proteasome. Don’t take this for granted, some nervous diseases like Alzheimer’s diseases is caused by the accumulation of misfolded proteins that can not be degraded timely.
Post-translational modification of proteins can also regulate gene expression. Such as histone Ubiquitinylation, acetylation and methylation.
However, there are still a lot of biological significance of post-translational modifications that is unknown to human beings and still many types of it has not yet been found. This, makes the research of it always being a hot topic in the field of life sciences.