SLBP

Stem-loop binding protein
Available structures
PDB Ortholog search: PDBe, RCSB
Identifiers
Symbols SLBP ; HBP
External IDs OMIM: 602422 MGI: 108402 HomoloGene: 31389 GeneCards: SLBP Gene
RNA expression pattern
More reference expression data
Orthologs
Species Human Mouse
Entrez 7884 20492
Ensembl ENSG00000163950 ENSMUSG00000004642
UniProt Q14493 P97440
RefSeq (mRNA) NM_001306074 NM_001289724
RefSeq (protein) NP_001293003 NP_001276653
Location (UCSC) Chr 4:
1.69 – 1.71 Mb
Chr 5:
33.63 – 33.65 Mb
PubMed search

Histone RNA hairpin-binding protein or stem-loop binding protein (SLBP) is a protein that in humans is encoded by the SLBP gene.[1][2][3]

Species distribution

SLBP has been cloned from humans, C. elegans, D. melanogaster, X. laevis, and sea urchins. The full length human protein has 270 amino acids (31 kDa) with a centrally located RNA binding domain (RBD). The 75 amino acid RBD is well conserved across species, however the remainder of SLBP is highly divergent in most organisms and not homologous to any other protein in the eukaryotic genomes.

Function

This gene encodes a protein that binds to the histone 3' UTR stem-loop structure in replication-dependent histone mRNAs. Histone mRNAs do not contain introns or polyadenylation signals, and are processed by a single endonucleolytic cleavage event downstream of the stem-loop. The stem-loop structure is essential for efficient processing of the histone pre-mRNA but this structure also controls the transport, translation and stability of histone mRNAs. SLBP expression is regulated during S-phase of the cell cycle, increasing more than 10-fold during the latter part of G1.

All SLBP proteins are capable of forming a highly stable complex with histone stem-loop RNA. Complex formation with the histone mRNA stem-loop is achieved by a novel three-helix bundle fold. SLBP proteins also recognize the tetraloop structure of the histone hairpin, the base of the stem, and the 5' flanking region. The crystal structure of human SLBP in complex with the stem-loop RNA as well as the exonuclease Eri1 reveals that the Arg181 residue of SLBP specifically interacts with the second guanine base in the RNA stem.[4]The rest of the protein is intrinsically disordered in fruit-flies as well as in humans. A unique feature of the SLBP RBD is that it is phosphorylated in its RNA binding domain at the Thr171 residue. The SLBP RBD also undergoes proline isomerization about this sequence and is a substrate for the prolyl isomerase Pin1. The N-terminal domain of human SLBP is required for translation activation of histone mRNAs via its interaction with SLIP1. SLBP also interacts with the CBP80 associated protein CTIF to facilitate rapid degradation of histone mRNAs. SLBP is a phosphoprotein and besides T171, it is also phosphorylated at Ser7, Ser20, Ser23, Thr60, Thr61 in mammalian cells. The phosphorylation at Thr60 is mediated by CK2 and Thr61 is by Cyclin A/Cdk1.[3]

References

  1. Martin F, Schaller A, Eglite S, Schumperli D, Muller B (Mar 1997). "The gene for histone RNA hairpin binding protein is located on human chromosome 4 and encodes a novel type of RNA binding protein". EMBO J 16 (4): 769–78. doi:10.1093/emboj/16.4.769. PMC 1169678. PMID 9049306.
  2. McCombie WR, Martin-Gallardo A, Gocayne JD, FitzGerald M, Dubnick M, Kelley JM, Castilla L, Liu LI, Wallace S, Trapp S (August 1992). "Expressed genes, Alu repeats and polymorphisms in cosmids sequenced from chromosome 4p16.3". Nat. Genet. 1 (5): 348–53. doi:10.1038/ng0892-348. PMID 1338771.
  3. 1 2 "Entrez Gene: SLBP stem-loop (histone) binding protein".
  4. Dazhi Tan, William F. Marzluff, Zbigniew Dominski, Liang Tong (Jan 2013). "Structure of Histone mRNA Stem-Loop, Human Stem-Loop Binding Protein, and 3′hExo Ternary Complex". Science 339 (6117): 318–321. doi:10.1126/science.1228705. PMC 3552377. PMID 23329046.

Further reading

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