why-is-the-bond-between-ubiquitin-and-lysines-r-group-not-considered-a-peptide-b

Question

Why is the bond between ubiquitin and lysine's R group not considered a peptide bond?

Accepted Answer

Because it is not part of the protein backbone.

Answer

Because it does not involve a carbonyl group.

Answer

Because it is weaker than a peptide bond.

Answer

Because it is only found in prokaryotic organisms.