Methods and compositions for targeting polyubiquitin

A nucleic acid molecule that encodes an antibody that specifically binds to a first polyubiquitin comprising a first lysine linkage between a lysine residue of one ubiquitin molecule and the C-terminal glycine residue of another ubiquitin molecule, wherein the antibody does not specifically bind to a second polyubiquitin comprising a second lysine linkage between a second lysine residue of one ubiquitin molecule and the C-terminal glycine residue of another ubiquitin molecule, and wherein the first lysine linkage differs from the second lysine linkage.

A nucleic acid molecule that encodes an antibody that specifically binds lysine-48-linked polyubiquitin, wherein the antibody does not specifically bind monoubiquitin, wherein said antibody specifically binds lysine-48-linked polyubiquitin with high affinity but binds lysine-63-linked polyubiquitin with substantially reduced affinity or does not specifically bind lysine-63-linked polyubiquitin.

A nucleic acid molecule that encodes an antibody that specifically binds to lysine-63-linked polyubiquitin, wherein the antibody does not specifically bind to monoubiquitin, wherein said antibody specifically binds lysine-63-linked polyubiquitin with high affinity but binds lysine-48-linked polyubiquitin with substantially reduced affinity or does not specifically bind lysine-48-linked polyubiquitin.