InterPro domain: IPR039924

pLCln also functions as a Sm chaperone in the stepwise snRNP assembly process [ 1 ]. snRNPs is a RNA-protein complex esessential to the removal of introns from pre-mRNA [ 2 , 3 ]. In humans, the core of snRNPs is composed of seven Sm proteins bound to snRNA. pLCln tethers the hetero-oligomers SmD1/D2 and SmE/F/G into a ring-shaped 6S complex, which subsequently docks onto the SMN complex. The SMN complex then removes pICln and enables the transfer of pre-assembled Sm proteins onto snRNA [ 4 ]. Consistent with the role of human pICln, the orthologue from S. pombe is required for optimal production of the spliceosomal snRNPs and for efficient splicing [ 5 ].

ICln, known as methylosome subunit pICln or chloride conductance regulatory protein ICln, owes these different names to its function in multiple regulatory pathways [ 6 ] as different as ion permeation, ribonucleoprotein biosynthesis and cytoskeletal organisation [ 7 ]. ICln can be identified both in the cytosol and in the cellular membrane, where it functions as a chloride current regulator and is important in regulating volume decrease after cellular swelling [ 8 , 9 , 10 , 11 ].

This entry includes ICln from animal and plants, and Lot5 from fungi. The function of Lot5 (low temperature responsive 5) is not known [ 12 ].

1. Methylation of Sm proteins by a complex containing PRMT5 and the putative U snRNP assembly factor pICln. Curr. Biol. 187, 43-9
2. Role of pICLn in methylation of Sm proteins by PRMT5. J. Biol. Chem. 11, 1990-4
3. pICln inhibits snRNP biogenesis by binding core spliceosomal proteins. Mol. Cell. Biol. 19, 4113-20
4. Structural Basis of Assembly Chaperone- Mediated snRNP Formation. Mol. Cell 49, 692-703
5. Characterization and in vivo functional analysis of the Schizosaccharomyces pombe ICLN gene. Mol. Cell. Biol. 284, 21347-59
6. The ICln interactome. Acta Physiol (Oxf) 273, 10811-4
7. pICln binds to a mammalian homolog of a yeast protein involved in regulation of cell morphology. J. Biol. Chem. 33, 2012-27
8. Cl- homeostasis in includer and excluder citrus rootstocks: transport mechanisms and identification of candidate genes. Plant Cell Environ. 140, 197-203
9. Molecular and electrophysiological characterization of nucleotide-sensitive chloride current-inducing protein of Fasciola hepatica. Mol. Biochem. Parasitol. 148, 1118-30
10. Hypotonicity induces aquaporin-2 internalization and cytosol-to-membrane translocation of ICln in renal cells. Endocrinology 23, 397-406
11. Quaternary structure assessment of ICln by fluorescence resonance energy transfer (FRET) in vivo. Cell. Physiol. Biochem. 283, 531-5
12. Multiple mechanisms regulate expression of low temperature responsive (LOT) genes in Saccharomyces cerevisiae. Biochem. Biophys. Res. Commun.