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Nucleo-cytoplasmic distribution of human hnRNP proteins: a search for the targeting domains in hnRNP A1.
J Cell Sci. 1995 Feb; 108 (Pt 2):545-55.JC

Abstract

hnRNP A1 (34 kDa) is an RNA binding protein consisting of two tandemly arranged RNA binding domains C-terminally linked to a glycine-rich auxiliary domain (2 x RBD-Gly). A1 belongs to the set of polypeptides that bind nascent hnRNA in the nucleus to form the so called hnRNP complexes. These complexes seem to be involved both in pre-mRNA processing and in the nuclear export of mRNA. In fact A1, along with other hnRNP proteins, is exported from the nucleus probably bound to mRNA and is immediately re-imported. A1 nuclear re-import, which requires active transcription, is not mediated by a canonical nuclear localisation signal (NLS). To identify the determinants of A1 subcellular localisation we developed an expression vector for studying the localisation, in transiently transfected cells, of the different structural motifs of A1 fused to a small reporter protein (chloramphenicol acetyltransferase, CAT; 26 kDa). We demonstrate that a 30 amino acid sequence in the glycine-rich domain (YNDFGNYNNQSSNFGPMKGGNFGGRSSGPY), which bears no resemblance to canonical NLS, is necessary and sufficient to target the protein to the nucleus. Our data suggest that this targeting sequence might act by mediating the interaction of A1 with a NLS-containing nuclear import complex. On the other hand, the nuclear export of A1 requires at least one RNA binding domain in accord with the hypothesis that A1 exits from the nucleus bound to mRNA. We propose a mechanism for the nucleo-cytoplasmic shuttling of A1 that envisages a specific role for the different structural domains and can explain the dependence of nuclear import from active transcription.

Authors+Show Affiliations

Istituto di Genetica Biochimica ed Evoluzionistica del CNR, Università degli Studi di Pavia, Italy.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

7769000

Citation

Weighardt, F, et al. "Nucleo-cytoplasmic Distribution of Human hnRNP Proteins: a Search for the Targeting Domains in hnRNP A1." Journal of Cell Science, vol. 108 (Pt 2), 1995, pp. 545-55.
Weighardt F, Biamonti G, Riva S. Nucleo-cytoplasmic distribution of human hnRNP proteins: a search for the targeting domains in hnRNP A1. J Cell Sci. 1995;108 (Pt 2):545-55.
Weighardt, F., Biamonti, G., & Riva, S. (1995). Nucleo-cytoplasmic distribution of human hnRNP proteins: a search for the targeting domains in hnRNP A1. Journal of Cell Science, 108 (Pt 2), 545-55.
Weighardt F, Biamonti G, Riva S. Nucleo-cytoplasmic Distribution of Human hnRNP Proteins: a Search for the Targeting Domains in hnRNP A1. J Cell Sci. 1995;108 (Pt 2):545-55. PubMed PMID: 7769000.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Nucleo-cytoplasmic distribution of human hnRNP proteins: a search for the targeting domains in hnRNP A1. AU - Weighardt,F, AU - Biamonti,G, AU - Riva,S, PY - 1995/2/1/pubmed PY - 1995/2/1/medline PY - 1995/2/1/entrez SP - 545 EP - 55 JF - Journal of cell science JO - J Cell Sci VL - 108 (Pt 2) N2 - hnRNP A1 (34 kDa) is an RNA binding protein consisting of two tandemly arranged RNA binding domains C-terminally linked to a glycine-rich auxiliary domain (2 x RBD-Gly). A1 belongs to the set of polypeptides that bind nascent hnRNA in the nucleus to form the so called hnRNP complexes. These complexes seem to be involved both in pre-mRNA processing and in the nuclear export of mRNA. In fact A1, along with other hnRNP proteins, is exported from the nucleus probably bound to mRNA and is immediately re-imported. A1 nuclear re-import, which requires active transcription, is not mediated by a canonical nuclear localisation signal (NLS). To identify the determinants of A1 subcellular localisation we developed an expression vector for studying the localisation, in transiently transfected cells, of the different structural motifs of A1 fused to a small reporter protein (chloramphenicol acetyltransferase, CAT; 26 kDa). We demonstrate that a 30 amino acid sequence in the glycine-rich domain (YNDFGNYNNQSSNFGPMKGGNFGGRSSGPY), which bears no resemblance to canonical NLS, is necessary and sufficient to target the protein to the nucleus. Our data suggest that this targeting sequence might act by mediating the interaction of A1 with a NLS-containing nuclear import complex. On the other hand, the nuclear export of A1 requires at least one RNA binding domain in accord with the hypothesis that A1 exits from the nucleus bound to mRNA. We propose a mechanism for the nucleo-cytoplasmic shuttling of A1 that envisages a specific role for the different structural domains and can explain the dependence of nuclear import from active transcription. SN - 0021-9533 UR - https://www.unboundmedicine.com/medline/citation/7769000/Nucleo_cytoplasmic_distribution_of_human_hnRNP_proteins:_a_search_for_the_targeting_domains_in_hnRNP_A1_ L2 - http://jcs.biologists.org/cgi/pmidlookup?view=long&pmid=7769000 DB - PRIME DP - Unbound Medicine ER -