|Safety Information according to GHS|
|Storage and Shipping Information|
|Storage Conditions||6 months at -70°C|
|Material Size||250 µg|
|Reference overview||Pub Med ID|
|Expression, purification, crystallization, and biochemical characterization of a recombinant protein phosphatase. |
Zhuo, S, et al.
J. Biol. Chem., 268: 17754-61 (1993) 1993
A protein phosphatase (PPase) from the bacteriophage lambda was overexpressed in Escherichia coli. The recombinant enzyme was purified to homogeneity yielding approximately 17 mg of enzyme from a single liter of bacterial culture. Biochemical characterization of the enzyme showed that it required Mn2+ or Ni2+ as an activator. The recombinant enzyme was active toward serine, threonine, and tyrosine phosphoproteins and phosphopeptides. Surprisingly, the bacterial histidyl phosphoprotein, NRII, was also dephosphorylated by the lambda-PPase. The lambda-PPase shares a number of kinetic and structural properties with the eukaryotic Ser/Thr phosphatases, suggesting that the lambda-PPase will serve as a good model for structure-function studies. Crystallization of the recombinant purified lambda-PPase yielded monoclinic crystals. The crystals diffract to 4.0 A when exposed to synchrotron x-ray radiation.
|Discovery of a protein phosphatase activity encoded in the genome of bacteriophage lambda. Probable identity with open reading frame 221. |
Cohen, P T and Cohen, P
Biochem. J., 260: 931-4 (1989) 1989
Infection of Escherichia coli with phage lambda gt10 resulted in the appearance of a protein phosphatase with activity towards 32P-labelled casein. Activity reached a maximum near the point of cell lysis and declined thereafter. The phosphatase was stimulated 30-fold by Mn2+, while Mg2+ and Ca2+ were much less effective. Activity was unaffected by inhibitors 1 and 2, okadaic acid, calmodulin and trifluoperazine, distinguishing it from the major serine/threonine-specific protein phosphatases of eukaryotic cells. The lambda phosphatase was also capable of dephosphorylating other substrates in the presence of Mn2+, although activity towards 32P-labelled phosphorylase was 10-fold lower, and activity towards phosphorylase kinase and glycogen synthase 25 50-fold lower than with casein. No casein phosphatase activity was present in either uninfected cells, or in E. coli infected with phage lambda gt11. Since lambda gt11 lacks part of the open reading frame (orf) 221, previously shown to encode a protein with sequence similarity to protein phosphatase-1 and protein phosphatase-2A of mammalian cells [Cohen, Collins, Coulson, Berndt & da Cruz e Silva (1988) Gene 69, 131-134], the results indicate that ORF221 is the protein phosphatase detected in cells infected with lambda gt10. Comparison of the sequence of ORF221 with other mammalian protein phosphatases defines three highly conserved regions which are likely to be essential for function. The first of these is deleted in lambda gt11.