This family contains proteins that are involved in nonsense mediated mRNA decay. A process that is triggered by premature stop codons in mRNA. The family includes Smg-4 [1] and UPF3.

1: Molecular identification of smg-4, required for mRNA surveillance in C. elegans. Aronoff R, Baran R, Hodgkin J; Gene 2001;268:153-164. PMID:11368911