The domain encoded by exon 2 of the survival motor neuron protein mediates nucleic acid binding [published erratum appears in Hum Mol Genet 1998 Oct;7(11):1831]

Spinal muscular atrophy (SMA) is a motor neuron disorder resulting fromanterior horn cell death. Survival motor neuron ( SMN ) is the SMA-determining gene and is deleted or gene converted in >95% of SMApatients. The SMN protein has a role in spliceosomal snRNP biogenesis andhas therefore been implicated indirectly in general cellular RNA processingdue to its unique sub-nuclear localization within structures termed 'gems',which co-localize with spliceosomal factors within coiled bodies. In thisreport, direct SMN RNA-binding activity, in addition to ssDNA and dsDNAbinding is demonstrated. The region of SMN encoded by exon 2 is necessaryand sufficient to mediate its nucleic acid-binding activities. This domainis homologous to several nucleic acid-binding factors, including severalhigh mobility group (HMG) proteins. Additionally, previously reported SMNmissense mutations isolated from SMA patients demonstrated reducedRNA-binding activity, suggesting that nucleic acid binding is functionallysignificant.