RT Journal Article
SR Electronic
T1 Single mRNP analysis by super-resolution microscopy and fluorescence correlation spectroscopy reveals that small mRNP granules represent mRNA singletons
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 558098
DO 10.1101/558098
A1 Àngels Mateu-Regué
A1 Jan Christiansen
A1 Frederik Otzen Bagger
A1 Christian Hellriegel
A1 Finn Cilius Nielsen
YR 2019
UL http://biorxiv.org/content/early/2019/05/11/558098.abstract
AB Small cytoplasmic mRNP granules are implicated in mRNA transport, translational control and decay. Employing Super-resolution Microscopy and Fluorescence Correlation Spectroscopy, we analyzed the molecular composition and dynamics of single cytoplasmic YBX1_IMP1 mRNP granules in live cells. Granules appeared elongated and branched with patches of IMP1 and YBX1 distributed along mRNA, reflecting the attachment of the two RNA-binding proteins in cis. Particles form at the nuclear pore and are spatially segregated from translating ribosomes, so the mRNP is a repository for mRNAs awaiting translation. In agreement with the average number of mRNA-binding sites derived from CLIP analyses, individual mRNPs contain 5 to 15 molecules of YBX1 and IMP1 and a single poly(A) tail identified by PABPC1. Taken together, we conclude that small cytoplasmic mRNP granules are mRNA singletons, thus depicting the cellular transcriptome. Consequently, expression of functionally related mRNAs in RNA regulons is unlikely to result from coordinated assembly.