The goal of my postdoctoral research is to explore potential
roles for the Signal Recognition Particle 9/14 (SRP9/14)
complex proteins in primate cells, where they are intriguingly
expressed over 20-fold higher than the other protein components
of the larger signal recognition particle (SRP). All secreted
and membrane-destined proteins encode a leader or signal peptide
that constitutes the first part of the nascent protein to exit
the ribosome. Signal peptide recognition by the SRP signal
domain causes the SRP RNA to bend 90° and insert its Alu
Domain (bound by SRP9 and SRP14) into the ribosome where, through
making tRNA-like contacts, it halts translation by preventing
the association of any further tRNAs. Since cytoplasmic SRP9/14
(in complex with small cytoplasmic Alu RNAs) exists free from
the full Signal Recognition Particle, I am exploring mechanisms
by which scAlus bound by SRP9 and SRP14 could potentially halt
translation of human 3' UTRs containing Alu repeat sequences.
