Nuclear localization and cell cycle regulation of a murine protein tyrosine phosphatase.
MPTP is a murine homolog of the human T-cell protein tyrosine phosphatase (PTPase) and the rat PTP-S enzyme. Enzymatic activity of this ubiquitously expressed protein was demonstrated in immunoprecipitates from NIH 3T3 cells and in recombinant protein overexpressed in bacteria. Expression of beta-galactosidase-MPTP MPTP chimeric proteins in COS1 cells identified a nuclear localization signal at the carboxyl terminus of the MPTP that was sufficient to direct beta-galactosidase as well as a tagged version of the MPTP to the nucleus. Deletion analysis of amino acids within the nuclear targeting signal showed that this sequence does not conform to the bipartite type of nuclear localization signals. Furthermore, it was shown that the steady-state levels of MPTP RNA fluctuate in a cell cycle-specific manner. On the basis of these experiments, we discuss the possible function of MPTP in the cell cycle and other nuclear processes.
Tillmann
U
U
Laboratory of Mammalian Genes and Development, National Institute of Child Health and Human Development, Bethesda, Maryland 20892.
Wagner
J
J
Boerboom
D
D
Westphal
H
H
Tremblay
M L
ML
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002453:Cell Cycle / Q000502:physiology*; D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology*; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D016384:Consensus Sequence; D017931:DNA Primers; D015870:Gene Expression; D006801:Humans; D007700:Kinetics; D051379:Mice; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017027:Protein Tyrosine Phosphatases / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D013601:T-Lymphocytes / Q000201:enzymology*; D013997:Time Factors; D014162:Transfection; D001616:beta-Galactosidase / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism
D017931:DNA Primers; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D017027:Protein Tyrosine Phosphatases; D001616:beta-Galactosidase