Ubiquitin Structure & Function: Difference between revisions
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One interesting characteristic of ubiquitin is its stability. Ubiquitin is able to withstand a range of pH levels and temperatures and is very resistant to tryptic digestion, while still containing seven Lysine and four arginine residues<ref name="2.8Aref">PMID: 2987935</ref>. Many aspects of ubiquitin's structure aid in this durability. Ubiquitin contains a hydrophobic core. Three hydrophobic residues found on the α-helix and 11 of the 13 hydrophobic residues from the β-sheet are involved in constructing this hydrophobic core. The main contributor to the ubiquitin stability is the vast amount of hydrogen-bonding interactions observed. The whole structure of ubiquitin undergoes significant hydrogen bonding, aside from the COOH terminus. | One interesting characteristic of ubiquitin is its stability. Ubiquitin is able to withstand a range of pH levels and temperatures and is very resistant to tryptic digestion, while still containing seven Lysine and four arginine residues<ref name="2.8Aref">PMID: 2987935</ref>. Many aspects of ubiquitin's structure aid in this durability. Ubiquitin contains a hydrophobic core. Three hydrophobic residues found on the α-helix and 11 of the 13 hydrophobic residues from the β-sheet are involved in constructing this hydrophobic core. The main contributor to the ubiquitin stability is the vast amount of hydrogen-bonding interactions observed. The whole structure of ubiquitin undergoes significant hydrogen bonding, aside from the COOH terminus. | ||
[[image:lysubq.png| thumb |right | upright=2.0 |Ubiquitin structure with lysine residues highlighted in Yellow.]] | [[image:lysubq.png| thumb |right | upright=2.0 |Ubiquitin structure with lysine residues highlighted in Yellow.]] | ||
Secondary structures found throughout | Secondary structures found throughout ubiquitin include three and one half turns of α-helix, a short 3<sub>10</sub> helix, a mixed β-sheet with five strands and seven reverse turns. Several unusual secondary structures are also seen including parallel G1 β-bulge, two reverse Asx turns and a symmetrical hydrogen-bonding region between two helices and two reverse turns. | ||
=Function= | =Function= | ||
At first, ubiquitin was believed to be a hormone involed in inducing the differentiation of lymphocytes and activating adenylate cyclase <ref name="2.8Aref"/>. However, today, ubiquitin is primarily known for its role in intracellular ATP-dependent protein degradation. This is accomplished through the process of several seperate reactions: | At first, ubiquitin was believed to be a hormone involed in inducing the differentiation of lymphocytes and activating adenylate cyclase <ref name="2.8Aref"/>. However, today, ubiquitin is primarily known for its role in intracellular ATP-dependent protein degradation. This is accomplished through the process of several seperate reactions: | ||
