Serine/Threonine Kinase Receptor Associated Protein (STRAP)

Spliceosomal uridine-rich small nuclear ribonucleoprotein (snRNP) assembly is an active process mediated by the macromolecular SMN complex. This complex contains the SMN1 protein and 6 additional proteins named GEMIN2 (SIP1) to GEMIN7, according to their localization to nuclear structures termed gems.UNRIP is integrated into a complex with UNR or with the SMN complex in vivo in a mutually exclusive manner. In the latter case, UNRIP is recruited to the active SMN complex via a stable interaction with GEMIN7. However, unlike SMN and the gemins, UNRIP localized predominantly to the cytoplasm and was absent from gems/Cajal bodies. RNAi-induced reduction of UNRIP protein levels led to enhanced accumulation of SMN in the nucleus as evident by the increased formation of nuclear gems/Cajal bodies.