Removal of the mRNA 5′ cap structure, a key step in mRNA turnover, is catalysed by the Dcp1–Dcp2 complex (the decapping complex). Decay is initiated by poly-A shortening, and oligoadenylated mRNAs (but not polyadenylated mRNAs) are selectively decapped allowing their further degradation by the 5′ to 3′ exonuclease XRN1. The decapping activator complex is made up of the highly conserved heptameric Lsm1p–7p complex (made up of the seven Like Sm proteins, Lsm1p–Lsm7p) and their interacting partner, Pat1p. It activates decapping by an unknown mechanism and localizes with other decapping factors to the P-bodies in the cytoplasm. See GW bodies.
Subjects: Medicine and Health.