Question

eschewed EnzymesFurther study of these proteins reveals them to be highly advanced proteins capable of passing through membranes despite their size. Researchers in another lab have managed to create an enzyme that is capable of recognizing an amino acid sequence that is unique to each of these toxic compounds and present on all of them. This enzyme, the researchers named Ripley1, is able to attach a ubiquitin molecule to the toxic proteins. What will happen to these toxins in a cell if they are ubiquitinated?Early treatments of plants with Ripley1 has shown that it has exceptional difficulty localizing itself into the plant cells. What chemical characteristics of this Ripley1 protein are likely preventing it from entering the plant cells?It was observed that animal cells are able to uptake the enzyme Ripley1. What method of cellular eating is most likely being used by these cells to take up the Ripley1 proteins?

Answer 1

• Ubiquitination would lead to the degradation of toxic protein by an ATP dependent process involving three steps like activation of the toxic protein ubiquitin-activating enzymes called E1, conjugating with ubiquitin-conjugating enzymes called E2 and ligation using ubiquitin ligases called E3. This happens via 26S proteosome which is found in all the cells and is responsible for the removal of toxic proteins.
• Amino acids are repelled by the hydrophobic tails associated with the lipid bilayer. Small nonpolar amino acids can localize through the cells whereas large polar or ionic molecules cannot localize through the cell. Hence Ripley1 protein must be large polar and ionic molecule which might be preventing it from localizing in the cell.
• The type of cellular eating utilized would be phagocytosis which would lead to the ingestion of the Ripley proteins by the formation of endocytic vesicles called phagosomes.