Target RNA recognition drives PIWI complex assembly for transposon silencing.

PIWI-clade Argonaute proteins and their associated PIWI-interacting RNAs (piRNAs) are essential guardians of genome integrity, silencing transposable elements through distinct nuclear and cytoplasmic pathways. Nuclear PIWI proteins direct heterochromatin formation at transposon loci, while cytoplasmic PIWIs cleave transposon transcripts to initiate piRNA amplification. Both processes rely on target RNA recognition by PIWI-piRNA complexes, yet how this leads to effector recruitment is unclear.

Structure of the human 20S U5 snRNP.

The 20S U5 small nuclear ribonucleoprotein particle (snRNP) is a 17-subunit RNA-protein complex and a precursor of the U4/U6.U5 tri-snRNP, the major building block of the precatalytic spliceosome. CD2BP2 is a hallmark protein of the 20S U5 snRNP, absent from the mature tri-snRNP.