SMG7 Homolog, Nonsense Mediated mRNA Decay Factor (SMG7)

SMG7 is involved in nonsense-mediated mRNA decay . The deduced protein contains an ATP/GTP-binding site motif A and a putative transmembrane domain. Northern blot analysis detected moderate SMG7 expression in all tissues and cell lines examined.Both SMG7 isoforms have a leucine zipper not found in the C. elegans protein. Western blot analysis detected endogenous SMG7 proteins of 135 and 140 kD. Cell fractionation experiments showed that both SMG7 isoforms were predominantly cytosolic, but they accumulated in nuclei following treatment with a nuclear export inhibitor.Mutations in the phosphoserine-binding site of SMG7 impaired SMG7-UPF7 binding and recruitment of UPF1 to cytoplasmic mRNA decay foci (P bodies) in transfected HeLa cells.