Post-Translational Modification

A protein can continually react in the cell unless the cell receives a signal to stop. Then the cell is able to hinder the performance of the protein until it is needed again, thus avoiding having to waste the energy in destroying the protein when not in use and then transcribing and translating a new protein. Post-translational modifications affect an already made protein and are able to regulate that proteins function. Types of post-translational modifications include ubiquitination, phosphorylation and acetylation. Different modifications cause different results in different proteins, but the end result is a modification of the proteins original function. Post-translational modifications are not only for stopping a proteins actions, but also can also cause conformational changes and lead to active states. Nucleotide bonding and hydrolysis can work together in proteins to counterbalance each other. For instance, in the Ras protein, hydrolysis causes the bound GTP to lose a phosphate group and causes Ras to enter an inactive state. Nucleotide bonding acts to replace the now GDP with GTP when the protein needs to be active again. Regulating proteins is essential to making sure the cell runs properly and efficiently. Post-translational modifications are one of the ways this is accomplished.