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Product of the oncogene‐activating gene Tpr is a phosphorylated protein of the nuclear pore complex
Author(s) -
Bangs Peter L.,
Sparks Cynthia A.,
Odgren Paul R.,
Fey Edward G.
Publication year - 1996
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/(sici)1097-4644(19960401)61:1<48::aid-jcb7>3.0.co;2-2
Subject(s) - nuclear pore , nuclear protein , phosphoprotein , immunoprecipitation , biology , microbiology and biotechnology , nuclear localization sequence , gene product , nuclear lamina , phosphorylation , nuclear matrix , nuclear transport , fusion protein , protein a/g , nucleoporin , cytoplasm , biochemistry , gene , cell nucleus , gene expression , transcription factor , chromatin , recombinant dna
We have identified a component of the human nuclear pore complex and have shown that it is the product of a gene involved in oncogenic activation. A monoclonal antibody raised against purified nuclear matrix proteins recognizes a single protein with an electrophoretic mobility of approximately 300 kDa and stains the nuclear envelope in a punctate pattern typical of nuclear pores. The antibody was used to screen λgt11 human cDNA libraries, and the resulting clones were sequenced and compared to sequences in the Genbank database. An exact match was found with the human tpr (for translocated promoter region) gene, a gene shown previously to be involved in the oncogenic activation of several protein kinases. Double‐label immunofluorescent microscopy with the anti‐Tpr antibody and an antibody to the previously characterized nuclear pore complex protein nup153 confirms that Tpr is localized to the nuclear pore complex. Tpr is located on the cytoplasmic face of the nucleus, as demonstrated by immunofluorescent staining of cells permeabilized with digitonin. Tpr is a 2,349‐amino acid protein with extensive coiled‐coil domains and an acidic globular C‐terminus. The protein contains 10 leucine zipper motifs and numerous sites for phosphorylation by a variety of protein kinases. Immunoprecipitation of Tpr from 32 P‐orthophosphate‐labeled cells shows that it is a phosphoprotein. Potential functions for Tpr and possible mechanisms for the transforming activity of Tpr fusion proteins are discussed. © 1996 Wiley‐Liss, Inc.