The SMN complex plays an essential role in spliceosomal snRNP assembly in the cytoplasm and is required for pre-mRNA splicing in the nucleus (PubMed:23063131). It may also play a role in the metabolism of snoRNPs (PubMed:23063131). Required in motor neurons and proprioceptive neurons to ensure correct U12 intron splicing and proper levels of tmem41b mRNA (PubMed:23063131). Required for the maturation of motor neuron axonal branches and dendrites (PubMed:23063131, PubMed:29061699). Homodimer. Component of an import snRNP complex composed of kpnb1, rnut1, smn1 and znf259. Part of the core SMN complex that contains smn1, gemin2/sip1, ddx20/gemin3, gemin4, gemin5, gemin6, gemin7, gemin8 and strap/unrip. Interacts with ddx20, fbl, nola1, rnut1, syncrip and with several spliceosomal snRNP core Sm proteins, including snrpb, snrpd1, snrpd2, snrpd3, snrpe and ilf3 (By similarity). Interacts with elavl4 (PubMed:29061699). The Tudor domain mediates association with dimethylarginines, which are common in snRNP proteins. Decreased axonal branches and decreased dendrites in motor neurons (PubMed:29061699). Decreased GAP43 mRNA levels (PubMed:29061699). Morpholino knockdown of the protein causes severe defects in motor neuron axonal outgrowth, including truncations and abnormal branching (PubMed:23063131). Belongs to the SMN family.