“How does the cell know when and which proteins to degrade?”
Many researchers are seeking to answer this ultimate question, but even with the extensive research, nobody can really answer clearly. Proteins are continuously synthesized and degraded under regulations. Therefore, protein degradation is as important as protein synthesis. In this paper, ubiquitination, which involves in a protein degradation process, will be discussed along with the Ubiquitin Ligase, a major player in the mechanism.
Ubiquitination is a post-translational modification where ubiquitin, an 8kDa protein that is highly conserved in eukaryotes, is attached to a substrate protein (Lu et al., 2008). Ubiquitin is attached to a targeted protein through a sequential cascade which involves E1 activating, E2 conjugating, and E3 ligase enzymes. This ubiquitin tagging is necessary for many cellular processes, including cell cycle, transcriptional regulation, DNA repair mechanism, apoptosis, protein trafficking, and cell signaling (Miranda M, 2007).
1. Medical Interest
a. Ubiquitin Ligases as Cancer Targets and Biomarkers
The main function of the ubiquitin system was thought to be the role in protein degradation. However, it also plays a role in cellular regulation processes such as cell cycle, DNA damage signaling, and receptor endocytosis (Miranda M, 2007). Defects in this mechanism can lead to various diseases, including neurodegenerative disorders, cancer, viral infection, and inflammation. Hence, it has been a fascinating field for developing cancer targets and biomarkers.
b. Proteasome Inhibitor Drugs Using the Ubiquitin System
Drug targets using the ubiquitin system has been researched and few found drugs have been successful. In 2003, Food and Drug Admini...
... middle of paper ...
...iquitinated E2 oxyester was incubated and RNF4 was collected on amylose beads.
As in Figure 8 (left), ubiquitin-charged E2 was preferentially bound by RNF4 and free E2 interaction was weak. Also, the free ubiquitin binding was not able to be detected. The model in Figure 8 (right) also suggests the binding of E3 with ubiquitin-charged E2. Through this experiment, RING RNF4 has preference on ubiquitin-charged E2 over other players which allow us to understand the mechanism of ubiquitination better.
5. Conclusion
As a biochemist, I am interested in how the cell works in highly regulated manner. Ubiquitination, the degradation mechanism, has been a fascinating field for many researchers. From this enzyme project, ubiquitination pathway was introduced in step by step. Also, the mechanistic details of RNF4 E3 Ligase were investigated with various experimental data.
Pharmaceuticals have examined and found to ”work by changing the biological functions of the target cells in the body through chemical agents“ (Doweiko, 2015, p. 16). ”Many people in the past have thought that drugs that
... Thus, the loss of BRCA1 can result in defective DNA damage repair, abnormal centrosome duplication, cell-cycle arrest, growth retardation, increased apoptosis, genetic instability and tumorigenesis2. The study of BRCA1 mutation in mice may be used for new therapeutic approaches, although the cause of the mutation in BRCA gene is unclear.
The shape of the molecules is changing and so the enzyme molecules can no longer fit into the gaps in the substrate that they need to and therefore the enzymes have de – natured and can no longer function as they are supposed to and cannot do their job correctly. Changing the temperature: Five different temperatures could be investigated. Water baths were used to maintain a constant temperature. Water baths were set up at 40 degrees, 60 degrees and 80 degrees (Celsius). Room temperature investigations were also carried out (20 degrees).
Takahashi, Y., et al. “Analysis of Promoter binding by the E2F and pRB Families In Vivo: Distinct E2F Proteins Mediate Activation and Repression.” Genes 14 (2000): 804-816.
its work. It is called the “lock and key” hypothesis. Lock in the enzymes. key: The substrate of the.
The [ES] complex can then undergo two different pathways; the complex can dissociate to [E] and [S], at a rate of k or it can shift equilibrium to the left with a rate constant of k2 to form [E] and product [P]1. In this model, the breakdown of the ES complex to yield P is the overall rate-limiting step. Three assumptions of a Michaelis-Menton plot are that a specific [ES] complex in rapid equilibrium between [E] and [S] is a necessary intermediate, the amount of substrate is more than the amount of enzyme so the [S] remains constant, and that this plot follows steady state assumptions. Steady state assumptions states that the intermediate stays the same concentration even if the starting materials and products are constantly changing.2 The rapid equilibrium between enzyme and substrate, and the enzyme-substrate complex yields a mathematical description regarded as the Michaelis-Menton
The enzymes have active sites on their surfaces to allow the binding of a substrate through the help of coenzymes to form enzyme-substrate complex. The chemical reaction thus converts the substrate to a new product then released and the catalytic cycle proceeds.
Thought to be an oncogene, a gene that has potential in transforming normal cells into tumor cells, p53 was regarded as the most prominent tumor suppressor gene [1]. P53 is a gene which signals apoptosis (programmed cell death) if a cell cannot be repaired due to an extensive amount of damage. As stated in the textbook, p53 regulation occurs by an E3 ubiquitin-protein ligase known as MDM2 [1]. "Controlling the controller" is a statement that describes the molecular interaction where the presence of MDM2 targets the p53 for proteosome via degradation. With three main checkpoints in cell cycle, the literature states p53 functioning from G1 into S phase in a chaotic cell [2]. The normal state of cells is to keep p53 levels low in order to prevent uncontrolled apoptosis and random cell cycle arrest from occurring. In a further note, although p53 promotes apoptosis and cell cycle arrest, cancer may result from p53 unable to recognize the problematic site. In turn, a mutation in p53 may result engaging in new activities. These activities include cellular transformation, tumor metastasis,...
Studies on the VHL gene product, pVHL, have helped clarify cellular responses with changing oxygen availability in mammalian cells, which in turn has helped our understanding on how this product plays a role in heart attacks, cancer, and strokes (Kaelin, William G., 2002). The pVHL protein is primarily located in the cytoplasm, but it has the capability of moving between the cytoplasm and the nucleus. pVHL regulates two types of hypoxia-inducible transcription factors (HIF1 and HIF2) that functions in cellular response to oxygen deficiency (Vaganovs, P., et al., 2013). HIF is a helix-loop-helix transcription factor that consists of two subunits (HIFα and HIFβ) that regulate cellular responses when there is an inadequate supply of oxygen, otherwise referred to as hypoxia (Kim, Jenny J., 2010). HIFβ is continuously produced unlike HIFα, which is highly regulated through ubiquitination by pVHL (Kim, Jenny J., 2010). pVHL also plays an important role in ubiquitination or protein degradation of key proteins within the cell (Kim, Jenny J.,
As we discussed above that pharmacokinetic and pharmacodynamics can be seen as two sides of the same coin in order to gain better understanding of their efficacy and safety profiles.” Generally it is possible to make fairly robust predictions of the pharmacokinetic profile in man using in vitro systems and preclinical pharmacokinetic studies. A previously published survey on the causes of failure in drug development indicated that inappropriate pharmacokinetics were a major cause such as; factors as low bioavailability due to high extraction or poor absorption characteristics, short elimination half-life leading to short duration of action and excessive variability due to genetic or environmental factors. This observation has led to an increased emphasis on pharmacokinetic input to the drug discovery process throughout the pharmaceutical industry. However, it is important to realise that this may only permit the rejection of compounds to b...
Universal Healthcare by definition means healthcare for all. That would also mean that an insured persons rates would not be increased to cover the uninsured. Universal Healthcare is moral and just obligation. By promoting the health of our citizens we then promote our infrastructure as well.
thousands of different ways to form thousands of different proteins. each with a unique function in the body. Both the amino acids manufactured in the liver and those derived from the breakdown of the The proteins we eat are absorbed into the blood stream and taken up by the cells and tissues to build new proteins as needed.... ... middle of paper ... ...denatured by boiling, their chains are shortened to form gelatine.
Proteins are considered to be the most versatile macromolecules in a living system. This is because they serve crucial functions in all biological processes. Proteins are linear polymers, and they are made up of monomer units that are called amino acids. The sequence of the amino acids linked together is referred to as the primary structure. A protein will spontaneously fold up into a 3D shape caused by the hydrogen bonding of amino acids near each other. This 3D structure is determined by the sequence of the amino acids. The 3D structure is referred to as the secondary structure. There is also a tertiary structure, which is formed by the long-range interactions of the amino acids. Protein function is directly dependent on this 3D structure.
The first stage of the process is the unwinding of old strands of the parent DNA molecule. The two strands of the double helix are first separated by enzymes. Then, each strand acts as a template for t...
Ubiquitin-proteasome System and a renewed look at the importance of PKA and CaMKII in long term memory development.