|dc.description.abstract||The large ribosomal subunit of the ribosome is exported out of the nucleus with the
help of a protein known as Nmd3. Nmd3 interacts with the large ribosomal subunit
and provides a nuclear export signal, which recruits export receptors and thereby
facilitates subunit export from the nucleus. However, in order for more large
ribosomal subunits to be able to be exported from the nucleus, Nmd3 must be
released from the ribosome in the cytoplasm and recycled back to the nucleus.
Rpl10 is a protein of the large ribosomal subunit that is required for the release of
Nmd3 from the large ribosomal subunit and allows it to be recycled back to the
nucleus, though the exact mechanism of Nmd3 release is unknown. A mutant
NMD3 I112T I362T allele has been shown to suppress a mutant rpl10 G161D allele,
thus suggesting some type of interaction between the Nmd3 and Rpl10 proteins.
Further studies have shown that Nmd3 and Rpl10 do not physically interact with
each other; however, Rpl10 has been shown to interact with tRNA and rRNA, thus
possibly providing a means by which Rpl10 may indirectly affect Nmd3 release.
A genetic screen was devised to identify mutations in RPL10 that are dependent on
NMD3 I112T I362T for survival. These mutations in RPL10 were mapped onto the
atomic structure of Rpl10 in the ribosome. While the mutations did not map to any
one location on Rpl10, two clusters of three mutations each were identified, one
near the N-terminus of the protein and another near the C-terminus of the protein,
both containing residues that could interact with rRNA nearby, as well as residues
that could interact with other residues internal to Rpl10 and thus affect the overall
structure of the protein. Thus, it may be possible that Rpl10 affects Nmd3 release
indirectly through accommodation of Rpl10 onto the ribosome via protein-rRNA
interactions that affect Nmd3-rRNA interactions.||en