Recombinant Rabbit Methylosome subunit pICln (CLNS1A)

Function

Involved in both the assembly of spliceosomal snRNPs and the methylation of Sm proteins (By similarity). Chaperone that regulates the assembly of spliceosomal U1, U2, U4 and U5 small nuclear ribonucleoproteins (snRNPs), the building blocks of the spliceosome, and thereby plays an important role in the splicing of cellular pre-mRNAs (By similarity). Most spliceosomal snRNPs contain a common set of Sm proteins SNRPB, SNRPD1, SNRPD2, SNRPD3, SNRPE, SNRPF and SNRPG that assemble in a heptameric protein ring on the Sm site of the small nuclear RNA to form the core snRNP (Sm core) (By similarity). In the cytosol, the Sm proteins SNRPD1, SNRPD2, SNRPE, SNRPF and SNRPG are trapped in an inactive 6S pICln-Sm complex by the chaperone CLNS1A that controls the assembly of the core snRNP (By similarity). Dissociation by the SMN complex of CLNS1A from the trapped Sm proteins and their transfer to an SMN-Sm complex triggers the assembly of core snRNPs and their transport to the nucleus (By similarity)

Subcellular Location

Cytoplasm, cytosol; Nucleus; Cytoplasm, cytoskeleton

Tissue Specificity

Widely distributed but expressed more abundantly in nonpigmented ciliary epithelial cells than in pigmented ones

Subunit

Component of the methylosome, a 20S complex containing at least PRMT5/SKB1, WDR77/MEP50 and CLNS1A/pICln. May mediate SNRPD1 and SNRPD3 methylation. Forms a 6S pICln-Sm complex composed of CLNS1A/pICln, SNRPD1, SNRPD2, SNRPE, SNRPF and SNRPG; ring-like structure where CLNS1A/pICln mimics additional Sm proteins and which is unable to assemble into the core snRNP. Interacts with LSM10 and LSM11

• Wan X.L. et al. Cloning and functional expression of a swelling-induced chloride conductance regulatory protein, plCln, from rabbit ocular ciliary epithelium. — Biochem. Biophys. Res. Commun. (1997)
• Okada H. et al. Molecular cloning and expression of rabbit heart chloride channel. (DEC-)