This protein is a variation of LacI protein and has missense mutations at its third codon (proline->tyrosine) and 61st codon (serine->leucine). This causes a 10,000 fold increase in its binding affinity for the pLac promoter.
Notes
See parts K091125 and K091123 for design considerations
Source
The basic sequence for the LacI gene came from Ecogene.com.