SMN1 Antibody

Background:

This gene is part of a 500 kb inverted duplication onchromosome 5q13. This duplicated region contains at least fourgenes and repetitive elements which make it prone to rearrangementsand deletions. The repetitiveness and complexity of the sequencehave also caused difficulty in determining the organization of thisgenomic region. The telomeric and centromeric copies of this geneare nearly identical and encode the same protein. However,mutations in this gene, the telomeric copy, are associated withspinal muscular atrophy; mutations in the centromeric copy do notlead to disease. The centromeric copy may be a modifier of diseasecaused by mutation in the telomeric copy. The critical sequencedifference between the two genes is a single nucleotide in exon 7,which is thought to be an exon splice enhancer. Note that the nineexons of both the telomeric and centromeric copies are designatedhistorically as exon 1, 2a, 2b, and 3-8. It is thought that geneconversion events may involve the two genes, leading to varyingcopy numbers of each gene. The protein encoded by this genelocalizes to both the cytoplasm and the nucleus. Within thenucleus, the protein localizes to subnuclear bodies called gemswhich are found near coiled bodies containing high concentrationsof small ribonucleoproteins (snRNPs). This protein formsheteromeric complexes with proteins such as SIP1 and GEMIN4, andalso interacts with several proteins known to be involved in thebiogenesis of snRNPs, such as hnRNP U protein and the smallnucleolar RNA binding protein. Two transcript variants encodingdistinct isoforms have been described.