Pre-mRNA processing in eukaryotes is thought to take place on a multitude of nuclear ribonucleoprotein (RNP) complexes, the most abundant of them being the heterogeneous nuclear (hn) RNP complexes. The identification in mammalian nuclear extracts of a novel, less-abundant 70–110S heterogeneous RNP, named large heterogeneous nuclear RNP (LH-nRNP), has previously been reported by Aidinis, Sekeris and Guialis (1995) Nucleic Acids Res. 23, 2742–2753. The structural composition of the LH-nRNP complex has been determined following the production of polyclonal antibodies against the major protein constituents of the complex, the pair of the 72/74-kDa polypeptides. In the present study evidence is shown to prove that the 72/74-kDa proteins are members of the hnRNP M protein family, hereafter referred to as 72/74(M) polypeptides. The extensive application of two-dimensional gel electrophoresis, combined with specific immunoprecipitation and immunoblotting assays, has allowed the assignment of the 72/74(M) proteins to a subset of the hnRNP M family, characteristic of the presence of the LH-nRNP complex and distinct from the hnRNP-associated M1–M4 components. Moreover, the immunoselection of the LH-nRNP complex from [32P]orthophosphate-labelled HeLa cells, with the parallel application of UV irradiation, has permitted the identification of the 72/74(M) polypeptides as the sole protein constituents of the complex in direct contact with the RNA. It is proposed that LH-nRNP constitutes a discrete subset of hnRNP complexes, having a possible role in establishing specific interactions between hnRNP and nuclear-matrix protein components.
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Research Article|
August 23 2000
The 72/74-kDa polypeptides of the 70–110S large heterogeneous nuclear ribonucleoprotein complex (LH-nRNP) represent a discrete subset of the hnRNP M protein family
Panayiota KAFASLA;
Panayiota KAFASLA
1Laboratory of Molecular Biology, Institute of Biological Research and Biotechnology, The National Hellenic Research Foundation, 48 Vas. Constantinou Avenue, Athens 11635, Greece
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Meropi PATRINOU-GEORGOULA;
Meropi PATRINOU-GEORGOULA
1Laboratory of Molecular Biology, Institute of Biological Research and Biotechnology, The National Hellenic Research Foundation, 48 Vas. Constantinou Avenue, Athens 11635, Greece
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Apostolia GUIALIS
Apostolia GUIALIS
1
1Laboratory of Molecular Biology, Institute of Biological Research and Biotechnology, The National Hellenic Research Foundation, 48 Vas. Constantinou Avenue, Athens 11635, Greece
1To whom correspondence should be addressed (e-mail aguial@eie.gr).
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Publisher: Portland Press Ltd
Received:
December 16 1999
Revision Received:
May 31 2000
Accepted:
June 22 2000
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 2000
2000
Biochem J (2000) 350 (2): 495–503.
Article history
Received:
December 16 1999
Revision Received:
May 31 2000
Accepted:
June 22 2000
Citation
Panayiota KAFASLA, Meropi PATRINOU-GEORGOULA, Apostolia GUIALIS; The 72/74-kDa polypeptides of the 70–110S large heterogeneous nuclear ribonucleoprotein complex (LH-nRNP) represent a discrete subset of the hnRNP M protein family. Biochem J 1 September 2000; 350 (2): 495–503. doi: https://doi.org/10.1042/bj3500495
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