Dualspecificity Lambda Phosphatase useful for dephosphorylation serine, threonine or tyrosine residues
Danny Q. Hoang * Mary Ellen Simcox
Stratagene Cloning Systems, Inc.
Stratagene's recombinant Lambda Phosphatase is a dualspecificity protein phosphatase that has been produced as a fusion to Stratagene's novel affinity tag, the calmodulinbinding peptide. The tag simplifies purification of the enzyme and allows the enzyme to be removed subsequent to in vitro dephosphorylation of substrate proteins. The activity of the target protein can then be assayed in the absence of phosphatase activity. This feature is an essential advantage when the substrate protein itself is a protein phosphatase or protein kinase.
Protein phosphorylation governs many biological processes, including metabolism, gene expression, cytoskeletal architecture, cell adhesion and the cell cycle.1 The level of protein phosphorylation in cells is modulated by two large families of enzymes, the protein kinases and the protein phosphatases. Kinases and phosphatases are classified according to their substrate specificities as tyrosine, serine/ threonine or dualspecificity enzymes.2,3
Lambda phosphatase is a dualspecificity phosphatase4 that is
useful for dephosphorylating proteins phosphorylated on serine, threonine or
tyrosine residues. The enzyme can be used to determine whether a protein of
interest is phosphorylated by analyzing the protein by SDSPAGE, plus and minus
phosphatase treatment. Dephosphorylation results in a significant shift in
electrophoretic mobility. In addition to this general application, Stratagene's
novel Lambda Phosphatase is readily removable; binding to calmodulin affinity
resin completely eliminates lambda phosphatase activity. By using Stratagene's
Lambda Phosphatase, investigators are able to assay the activity of a