SLBP | |||||||||||||||||||||||||
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Identifiers | |||||||||||||||||||||||||
Aliases | SLBP , HBP, stem-loop binding protein | ||||||||||||||||||||||||
External IDs | OMIM: 602422 MGI: 108402 HomoloGene: 31389 GeneCards: SLBP | ||||||||||||||||||||||||
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Orthologs | |||||||||||||||||||||||||
Species | Human | Mouse | |||||||||||||||||||||||
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Ensembl | |||||||||||||||||||||||||
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Location (UCSC) | Chr 4: 1.69 – 1.71 Mb | Chr 5: 33.63 – 33.65 Mb | |||||||||||||||||||||||
PubMed search | [3] | [4] | |||||||||||||||||||||||
Wikidata | |||||||||||||||||||||||||
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Histone RNA hairpin-binding protein or stem-loop binding protein (SLBP) is a protein that in humans is encoded by the SLBP gene. [5] [6] [7]
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.
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. [8] 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. [7]
S phase (Synthesis Phase) is the phase of the cell cycle in which DNA is replicated, occurring between G1 phase and G2 phase. Since accurate duplication of the genome is critical to successful cell division, the processes that occur during S-phase are tightly regulated and widely conserved.
The histone 3′ UTR stem-loop is an RNA element involved in nucleocytoplasmic transport of the histone mRNAs, and in the regulation of stability and of translation efficiency in the cytoplasm. The mRNAs of metazoan histone genes lack polyadenylation and a poly-A tail, instead 3′ end processing occurs at a site between this highly conserved stem-loop and a purine rich region around 20 nucleotides downstream. The stem-loop is bound by a 31 kDa stem-loop binding protein. Together with U7 snRNA binding of the HDE, SLBP binding nucleates the formation of the processing complex.
The U7 small nuclear RNA is an RNA molecule and a component of the small nuclear ribonucleoprotein complex. The U7 snRNA is required for histone pre-mRNA processing.
5'-3' Exoribonuclease 2 (XRN2) also known as Dhm1-like protein is an exoribonuclease enzyme that in humans is encoded by the XRN2 gene.
Histone H3.1t is a protein that in humans is encoded by the HIST3H3 gene.
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Histone H2B type 1-K is a protein that in humans is encoded by the HIST1H2BK gene.
Histone H2B type 3-B is a protein that in humans is encoded by the HIST3H2BB gene.
Histone H2B type 1-D is a protein that in humans is encoded by the HIST1H2BD gene.
Histone H2B type 1-B is a protein that in humans is encoded by the HIST1H2BB gene.
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Histone H2A type 1-H is a protein that in humans is encoded by the HIST1H2AH gene.
Histone H2A type 1-B/E is a protein that in humans is encoded by the HIST1H2AB gene.
Histone H2B type 1-M is a protein that in humans is encoded by the HIST1H2BM gene.
Histone H2A type 1-A is a protein that in humans is encoded by the HIST1H2AA gene.
Histone H2A type 2-B is a protein that in humans is encoded by the HIST2H2AB gene.
U7 snRNA-associated Sm-like protein LSm10 is a protein that in humans is encoded by the LSM10 gene.
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