title: Nuclear localization of the PEP protein tyrosine phosphatase.
abstract: PEP is an intracellular protein tyrosine phosphatase expressed primarily by cells of hematopoietic origin that can be divided structurally into a catalytic domain and a large carboxy-terminal domain. The carboxy-terminal domain is enriched in proline, glutamic acid, serine, and threonine residues (PEST sequences) and contains a nonperfect tandem repeat sequence enriched in proline residues and a carboxy terminus enriched in basic amino acids. Here we show that PEP is diffusely expressed in lymphoid tissues, consistent with expression by many different cell types. Analysis of the PEP protein identifies a nuclear localization sequence within the extreme carboxy terminus. Transfer of 18 amino acids from the carboxy terminus of PEP to beta-galactosidase conferred nuclear localization, indicating that this sequence was sufficient for nuclear localization. Proteins enriched in PEST sequences are often rapidly degraded. However, pulse-chase analysis indicates that PEP has a half-life of greater than 5 h.
authors.affiliation: Howard Hughes Medical Institute, Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110.
authors.forename: E
authors.initials: E
authors.lastname: Flores
authors.forename: G
authors.initials: G
authors.lastname: Roy
authors.forename: D
authors.initials: D
authors.lastname: Patel
authors.forename: A
authors.initials: A
authors.lastname: Shaw
authors.forename: M L
authors.initials: ML
authors.lastname: Thomas
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000032:analysis / Q000096:biosynthesis; D001402:B-Lymphocytes / Q000201:enzymology; D015152:Blotting, Northern; D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology* / Q000648:ultrastructure; D002522:Chlorocebus aethiops; D000939:Epitopes / Q000032:analysis; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D017403:In Situ Hybridization; D007668:Kidney; D007700:Kinetics; D008221:Lymphoid Tissue / Q000201:enzymology*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12; D017027:Protein Tyrosine Phosphatases / Q000032:analysis / Q000096:biosynthesis*; D016271:Proto-Oncogene Proteins c-myc / Q000032:analysis / Q000096:biosynthesis; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000096:biosynthesis; D013950:Thymus Gland / Q000166:cytology / Q000201:enzymology*; D014162:Transfection; D001616:beta-Galactosidase / Q000096:biosynthesis
chemical_list: D000952:Antigens, Polyomavirus Transforming; D000939:Epitopes; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; C516738:PTPN12 protein, human; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12; D017027:Protein Tyrosine Phosphatases; D001616:beta-Galactosidase