Cells have evolved mechanism to get rid of nonfunctional or potentially deleterious proteins that are coded by mRNA with premature translation termination or mRNA without stop codon. The pathway of degradation of such mRNA have been described in mammals, flies, nematodes, yeast and plants. The degradation steps as well as factors involved in are not identical in different species. The general way of recognition of aberrant transcripts depends on spatial relationship between ribosome components and ribonucleoproteins bound to the 3’UTR sequence.