The Survival of Motor Neuron (SMN) is a protein involved in the assembly of snRNPs, the essential components of spliceosomal machinery. A lack of SMN due to SMN1 deletion results in widespread splicing defects, especially in spinal motor neurons, and is one cause of spinal muscular atrophy.
SMN also functions in transcriptional regulation, telomerase regeneration and cellular trafficking.
SMN is evolutionary conserved including the Fungi kingdom, though only fungal organisms with a great number of introns has the smn gene (or the spf30 paralogue). Surprisingly, these are filamentous fungus which have mycelia, so suggesting analogy to the neuronal axons.
^Sattler, M.; Selenko, P.; Sprangers, R.; Stier, G.; Bühler, D.; Fischer, U. (2001). "SMN tudor domain structure and its interaction with the Sm proteins". Nature Structural Biology8 (1): 27–31. doi:10.1038/83014. PMID11135666.edit
^Mier P, Pérez-Pulido AJ (2012). "Fungal Smn and Spf30 homologues are mainly present in filamentous fungi and genomes with many introns: implications for spinal muscular atrophy". Gene491 (2): 135–41. doi:10.1016/j.gene.2011.10.006. PMID22020225.