Unformatted text preview: α-Complementation as a Tool for Gene Cloning The E. colienzyme beta-galactosidase is a homo-tetramer of the protein product of the lacZgene. Certain mutations in the 5' region of lacZprevent subunit association. Because monomers lack enzyme activity, the failure to assemble leads to a Lac- phenotype. In some such mutants, subunit assembly (and enzyme activity) are restored by the presence of a small (26 amino acids) amino-terminal fragment of the lacZproduct (the so-called alpha polypeptide). Such lacZmutants are said to be subject to "α-complementation." The product of the allele lacZD M15 lacks amino acids 11-41 of wild-type beta-galactosidase and is subject to a complementation. Messing and co-workers took advantage of α-complementation in constructing the M13mp phage and pUC plasmid series of cloning vectors. These vectors carry a polycloning region embedded in the sequence for an alpha polypeptide gene fragment....
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This note was uploaded on 05/17/2011 for the course MCDB 101A taught by Professor Thrower during the Spring '08 term at UCSB.
- Spring '08