Nuclear-mitotic apparatus protein: a structural protein interface between the nucleoskeleton and RNA splicing.
Vertebrate splicing factors are localized to discrete domains within the nuclei of somatic cells. The mechanism whereby such nuclear domains, identified as speckles by immunofluorescence microscopy, are generated is unclear. Recent studies suggest that the spatial order within the nucleus is maintained by nuclear matrix factors. Here we show that a protein in the nuclear matrix and mitotic apparatus [nuclear-mitotic apparatus protein, NuMA; Lydersen, B. & Pettijohn, D. (1980) Cell 22, 489-499] colocalizes with splicing factors in interphase nuclei and is associated with small nuclear ribonucleoproteins in a complex immunoprecipitated from HeLa extract with small nuclear ribonucleoprotein antibodies. Moreover, NuMA associates with splicing complexes that are reconstituted in vitro using wild-type pre-mRNA, but not with nonspecific RNA. Cumulatively, these observations suggest a function of NuMA or NuMA-like proteins in interphase cells in providing a bridge between RNA processing and the nucleoskeleton.
Zeng
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Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030.
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Berget
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Brinkley
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D034961:Antigens, Nuclear; D018797:Cell Cycle Proteins; D002467:Cell Nucleus / Q000648:ultrastructure*; D005455:Fluorescent Antibody Technique; D006801:Humans; D007399:Interphase; D046911:Macromolecular Substances; D034521:Nuclear Matrix-Associated Proteins; D009687:Nuclear Proteins / Q000302:isolation & purification / Q000378:metabolism*; D011233:Precipitin Tests; D011485:Protein Binding; D012326:RNA Splicing; D017411:Ribonucleoproteins, Small Nuclear / Q000302:isolation & purification / Q000378:metabolism*; D017381:Spliceosomes / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D034961:Antigens, Nuclear; D018797:Cell Cycle Proteins; D046911:Macromolecular Substances; C050045:NUMA1 protein, human; D034521:Nuclear Matrix-Associated Proteins; D009687:Nuclear Proteins; D017411:Ribonucleoproteins, Small Nuclear