Patent ID: 8592179

Claim:
A method for producing a modified mammalian ubiquitin protein having a new or improved binding affinity with respect to an agent, the method comprising: a) selecting an unmodified mammalian ubiquitin protein comprising SEQ ID NO: 15; b) providing an agent to which the unmodified mammalian ubiquitin protein has low or no binding affinity; c) selecting at least four amino acids from among amino acids 16, 18, 20-22, 24, 25, 28, 29, 31-33, 38, 39, and 52-55 of SEQ ID NO: 15; d) substituting the selected at least four amino acids to produce a modified mammalian ubiquitin protein, wherein at least each of amino acids 22, 24, 25, and 28 of SEQ ID NO: 15 is substituted; e) contacting the modified mammalian ubiquitin protein with the agent provided in step b); and f) isolating a modified mammalian ubiquitin protein having a new or improved binding affinity with respect to the agent provided in step b, wherein a modified mammalian ubiquitin protein having a new or improved binding affinity with respect to the agent is produced.