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Cotranslational association of mRNA encoding subunits of heteromeric ion channels.

Authors :
Fang Liu
Jones, David K.
de Lange, Willem J.
Robertson, Gail A.
Source :
Proceedings of the National Academy of Sciences of the United States of America. 4/26/2016, Vol. 113 Issue 17, p4859-4864. 6p.
Publication Year :
2016

Abstract

Oligomers of homomeric voltage-gated potassium channels associate early in biogenesis as the nascent proteins emerge from the polysome. Less is known about howproteins emerging fromdifferent polysomes associate to form hetero-oligomeric channels. Here, we report that alternate mRNA transcripts encoding human ether-à-go-go-related gene (hERG) 1a and 1b subunits, which assemble to produce ion channels mediating cardiac repolarization, are physically associated during translation. We show that shRNA specifically targeting either hERG 1a or 1b transcripts reduced levels of both transcripts, but only when they were coexpressed heterologously. Both transcripts could be copurified with an Ab against the nascent hERG 1a N terminus. This interaction occurred even when translation of 1b was prevented, indicating the transcripts associate independent of their encoded proteins. The association was also demonstrated in cardiomyocytes, where levels of both hERG transcripts were reduced by either 1a or 1b shRNA, but native KCNE1 and ryanodine receptor 2 (RYR2) transcripts were unaffected. Changes in protein levels and membrane currents mirrored changes in transcript levels, indicating the targeted transcripts were undergoing translation. The physical association of transcripts encoding different subunits provides the spatial proximity required for nascent proteins to interact during biogenesis, and may represent a general mechanism facilitating assembly of heteromeric protein complexes involved in a range of biological processes. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00278424
Volume :
113
Issue :
17
Database :
Academic Search Index
Journal :
Proceedings of the National Academy of Sciences of the United States of America
Publication Type :
Academic Journal
Accession number :
114969337
Full Text :
https://doi.org/10.1073/pnas.1521577113