title: Expression profile and interactions of hnRNP A3 within hnRNP/mRNP complexes in mammals.
abstract: The hnRNP A/B family contains abundant nuclear proteins with major roles in alternative splicing and the ability for nucleo-cytoplasmic shuttling. Compared to the best known members of this family (hnRNP A1, A2/B1), hnRNP A3 is a relatively less known protein. We report herein immunochemical studies with the hnRNP A3 isoforms (A3a and A3b) that provided evidence for species-specific expression. The unspliced A3a was found in human and murine cells, while the spliced A3b was a unique and abundant isoform in mouse/rat. In addition, a tissue-specific variation was observed in mice, as the brain was the only tissue found to overexpress hnRNP A3a. Both hnRNP A3a and A3b were able to stably associate with immunoselected hnRNP and mRNP complexes. Use of the auxiliary domain of hnRNP A3 in pull-down assays on human cell extracts revealed its unique ability to form a network of interactions not only with other A/B proteins but also with additional hnRNPs. All interactions, except those of hnRNP A1, were highly enhanced by previous RNase A digestion of the extracts. Our findings revealed novel characteristics of hnRNP A3 and supported its extensive involvement in the many aspects of mRNA maturation processes along with the other hnRNP A/B proteins.
authors.affiliation: RNA Processing Program, Institute of Biological Research and Biotechnology, National Hellenic Research Foundation, 48 Vas. Constantinou Avenue, 11635 Athens, Greece.
authors.forename: Christina
authors.initials: C
authors.lastname: Papadopoulou
authors.forename: Georgios
authors.initials: G
authors.lastname: Boukakis
authors.forename: Vassiliki
authors.initials: V
authors.lastname: Ganou
authors.forename: Meropi
authors.initials: M
authors.lastname: Patrinou-Georgoula
authors.forename: Apostolia
authors.initials: A
authors.lastname: Guialis
mesh_terms: D000818:Animals; D002460:Cell Line; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000378:metabolism*; D006801:Humans; D051379:Mice; D011485:Protein Binding; D020033:Protein Isoforms / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism*; D059467:Transcriptome
chemical_list: C502034:HNRNPA3 protein, human; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D020033:Protein Isoforms; D012261:Ribonucleoproteins; C026452:messenger ribonucleoprotein