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Query: UNIPROT:P06889 (Mol)
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The 18S ribosomal RNAs of 21 tetrapods were sequenced and aligned with five published tetrapod sequences. When the coelacanth was used as an outgroup, Lissamphibia (living amphibians) and Amniota (amniotes) were found to be statistically significant monophyletic groups. Although little resolution was obtained among the lissamphibian taxa, the amniote sequences support a sister-group relationship between birds and mammals. Portions of the 28S ribosomal RNA (rRNA) molecule in 11 tetrapods also were sequenced, although the phylogenetic results were inconclusive. In contrast to previous studies, deletion or down-weighting of base-paired sites were found to have little effect on phylogenetic relationships. Molecular evidence for amniote relationships is reviewed, showing that three genes (beta-hemoglobin, myoglobin, and 18S rRNA) unambiguously support a bird-mammal relationship, compared with one gene (histone H2B) that favors a bird-crocodilian clade. Separate analyses of four other genes (alpha-crystallin A, alpha-hemoglobin, insulin, and 28S rRNA) and a combined analysis of all sequence data are inconclusive, in that different groups are defined in different analyses and none are strongly supported. It is suggested that until sequences become available from a broader array of taxa, the molecular evidence is best evaluated at the level of individual genes, with emphasis placed on those studies with the greatest number of taxa and sites. When this is done, a bird-mammal relationship is most strongly supported. When regarded in combination with the morphological evidence for this association, it must be considered at least as plausible as a bird-crocodilian relationship.
Mol Biol Evol 1990 Nov
PMID:Tetrapod phylogeny inferred from 18S and 28S ribosomal RNA sequences and a review of the evidence for amniote relationships. 156 Jul 70

As part of our studies on the cell cycle regulation of human histone gene expression, we examined the elements governing transcription of a human histone H2B gene in nuclear extracts derived from human HeLa cells. Circular templates were transcribed at 5- to 10-fold higher levels than were linear templates. A series of deletion, linker-substitution, and point mutants defined cis-acting promoter sequences that were recognized in nuclear extracts. These sequences extended from 118 to 21 base pairs 5' to the transcription initiation site. Elements recognized included (from 5' to 3') a series of direct repeats, a CCAAT homology, a human histone-specific hexamer, an H2B consensus element, and a TATA box. Sequence elements 5' to the hexamer were required for its function. In contrast, the H2B consensus element could function independently of more-5' promoter elements and in turn was essential for the function of upstream elements. An interesting feature of this consensus is that its core octanucleotide (ATTTGCAT) is found in several nonhistone genes. By comparison with functional elements in an H4 promoter, we infer that a combinatorial interaction of general and gene-specific factors may contribute to the S-phase elevation of H2B transcription.
Mol Cell Biol 1986 Oct
PMID:Multiple sequence elements are required for maximal in vitro transcription of a human histone H2B gene. 302 88

A physical map of 330 x 10(3) base-pairs near the replication origin of Myxococcus xanthus chromosome has been established already. Using DNA fragments from this region, Northern blot hybridization analysis was carried out in order to identify the genes expressed during vegetative growth. One of the genes, tentatively designated as vegA, was cloned and its entire DNA sequence was determined. The amino acid sequence of the gene product deduced from the DNA sequence reveals that the VegA protein is a very basic protein with a molecular weight of 18,700. The gene was expressed in Escherichia coli using an expression vector, and its gene product was identified using SDS/polyacrylamide gel electrophoresis. From the results of S1 nuclease mapping, the vegA promoter was found to contain the sequence TAGACA at the -35 region and the sequence AAGGGT at the -10 region. These two regions are separated by 18 nucleotides. Genetic analysis suggests that the vegA gene may be essential for the growth of M. xanthus. From a computer-aided search for homologies to know protein structures, it was found that the VegA protein has homologies to histone H4 of Tetrahymena thermophila and histone H2B of sea urchin.
J Mol Biol 1987 Aug 05
PMID:Identification of a vegetative promoter in Myxococcus xanthus. A protein that has homology to histones. 331 62

We isolated a chromosomal protein fraction derived from chromatin of sea urchin embryos which specifically stimulated the expression of the histone H2B gene by a factor of 5- to 10-fold when the complete sea urchin histone gene repeat h22 was injected in Xenopus laevis oocyte nuclei. Gene manipulation experiments revealed the existence of two different target sites in the H2B gene which appear to mediate the response to injection of the stimulatory sea urchin chromatin-associated proteins; both are located downstream of the transcription initiation site. The first sequence element which is shown to be implicated is within, or at least includes, the H2B 5' untranslated leader sequence between nucleotides 11 and 76. The second element resides within an H2B DNA segment located near the 3' end of the gene, extending from 90 base pairs upstream of the mRNA 3' terminus to 140 base pairs in the spacer sequences downstream.
Mol Cell Biol 1985 Oct
PMID:Stimulation of sea urchin H2B histone gene transcription by a chromatin-associated protein fraction depends on gene sequences downstream of the transcription start site. 383 83

The structural role of histone H2B from sea urchin sperm (H2Bsp) has been examined in experiments on reconstitution of chromatin from DNA and core histones taken in three variants: (1) four core histones from sea urchin sperm; (2) four core histones from calf thymus; (3) (H3, H4, H2A) from calf thymus and H2Bsp. It is shown that H2Bsp when present in reconstituted chromatin induces its aggregation. Fidelity of the reconstitution of nucleosomes has been tested using DNase I probe, one- and two-dimensional electrophoresis and electron microscopy. The reconstitutes that contain H2Bsp appear under electron microscope mainly as regular closely spaced large granules, about 450 A in diameter, which are very similar to the granules found in "native" sea urchin sperm chromatin. The reconstitutes formed by four core histones from calf thymus appear as randomly arranged particles, about 100 A in diameter. We conclude that histone H2Bsp participates in interactions between nucleosomes and is involved in the formation of the condensed supranucleosomal structure in sea urchin sperm chromatin.
Mol Biol (Mosk)
PMID:[The role of H2B histones from the sea urchin sperm in the formation of supranucleosome structures]. 403 46

A comparative study of the condensation of reconstituted complexes of circular SV40 DNA with core histones from calf thymus and sea urchin sperm was performed using sedimentation and electron microscopic techniques. It is shown that in low ionic strength solutions both types of complexes are similar to native 'minichromosomes'. In the region from 0.08 to 0.16 M NaCl the complexes of SV40 DNA with thymus histones form small compact particles. By contrast, the compaction of the SV40 DNA complexes with sperm histones results in the formation of giant intermolecular associates. The results obtained may mean that histone H2B of sea urchin sperm participates in the formation of a higher order structure in sperm chromatin.
Mol Biol Rep 1982 Mar 31
PMID:The role of histone H2B from sea urchin sperm in the association of reconstituted minichromosomes. 628 38

The CDC28 gene was subcloned from a plasmid containing a 6.5-kilobase-pair segment of Saccharomyces cerevisiae DNA YRp7(CDC28-3) by partial digestion with Sau3A and insertion of the resulting fragments into the BamHI sites of YRp7 and pRC1. Recombinant plasmids were obtained containing inserts of 4.4 and 3.1 kilobase pairs which were capable of complementing a cdc28(ts) mutation. R-loop analysis indicated that each yeast insert contained two RNA coding regions of about 0.8 and 1.0 kilobase pairs, respectively. In vitro mutagenesis experiments suggested that the smaller coding region corresponded to the CDC28 gene. When cellular polyadenylic acid-containing RNA, separated by agarose gel electrophoresis after denaturation with glyoxal and transferred to nitrocellulose membrane, was reacted with labeled DNA from the smaller coding region, and RNA species of about 1 kilobase in length was detected. Presumably, the discrepancy in size between the R-loop and electrophoretic determinations is due to a segment of polyadenylic acid which is excluded from the R-loops. By using hybridization of the histone H2B mRNAs to an appropriate probe as a previously determined standards, it was possible to estimate the number of CDC28 mRNA copies per haploid cell as between 6 and 12 molecules. Hybrid release translation performed on the CDC29 mRNA directed the synthesis of a polypeptide of 27,000 daltons, as determined by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. This polypeptide was not synthesized when mRNA prepared from a cdc28 nonsense mutant was translated in a parallel fashion. However, if the RNA from a cell containing the CDC28 gene on a plasmid maintained at a high copy number was translated, the amount of in vitro product was amplified fivefold.
Mol Cell Biol 1982 Apr
PMID:Preliminary characterization of the transcriptional and translational products of the Saccharomyces cerevisiae cell division cycle gene CDC28. 628 37

Biochemical purification and cognate cDNA cloning studies have revealed that the previously described transcriptional coactivator OCA-B consists of a 34- or 35-kDa polypeptide with sequence relationships to known coactivators that function by protein-protein interactions. Studies with a recombinant protein have proved that a single OCA-B polypeptide is the main determinant for B-cell-specific activation of immunoglobulin (Ig) promoters and provided additional insights into its mechanism of action. Recombinant OCA-B can function equally well with Oct-1 or Oct-2 on an Ig promoter, but while corresponding POU domains are sufficient for OCA-B interaction, and for octamer-mediated transcription of a histone H2B promoter, an additional Oct-1 or Oct-2 activation domain(s) is necessary for functional synergy with OCA-B. Further studies additional Oct-1 or Oct-2 activation domain(s) is necessary for functional synergy with OCA-B. Further studies show that Ig promoter activation by Oct-1 and OCA-B requires still other general (USA-derived) cofactors and also provide indirect evidence that distinct Oct-interacting cofactors regulate H2B transcription.
Mol Cell Biol 1995 Aug
PMID:Cloning, functional characterization, and mechanism of action of the B-cell-specific transcriptional coactivator OCA-B. 762 6

A uterus tyrosine kinase has been purified to a single 67-kDa protein when analyzed by SDS-PAGE. Under nondenaturing conditions the molecular weight of the enzyme ranges from 114 to 136 kDa, depending on the procedure employed. The kinase binds calmodulin in a Ca(2+)-dependent manner and the ATP analog [(fluorosulfonyl)benzoyl]adenosine. The purified enzyme phosphorylates the phosphatase-treated uterus estradiol receptor on tyrosine and activates its hormone binding. The kinase phosphorylates actin, calmodulin, and histone H2B. Whatever the substrate, the enzymic activity is dependent on purified estradiol-receptor complex and is activated by Ca(2+)-calmodulin. The kinase activates and phosphorylates the human estradiol receptor (HEO) within the hormone binding domain (HBD) [Migliaccio, et al. (1989) Mol Endocrinol. 3, 1061-1069] as well as four of the five mutants of the HEO obtained by substituting each of the five tyrosine residues present in the HBD of the receptor with phenylalanine by site-directed mutagenesis. The mutant substituted at tyrosine 537 is the only one that is neither phosphorylated nor activated by the kinase. This proves a causal relationship between the phosphorylation of estradiol receptor on tyrosine 537 and its hormone binding activity. A synthetic peptide corresponding to 11 out of 13 amino acids surrounding tyrosine at position 537 of the human estrogen receptor can be phosphorylated by the kinase. This and other findings indicate that this kinase, unlike other tyrosine kinases, phosphorylates tyrosyl residues with acidic amino acids close to the carboxyl side.
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PMID:Properties of a purified estradiol-dependent calf uterus tyrosine kinase. 767 22

Two wheat histone H2B genes (TH123 and TH153) were isolated. Nucleotide sequence analysis revealed that some characteristic sequence motifs were conserved in both the 5'- and 3'-flanking regions. A canonical TATA box and several CCAAT sequences were present in the presumed promoter regions. Motifs similar or identical to the hexamer (ACGTCA) and octamer (CGCGGATC) motifs that are positive cis-acting elements of the wheat H3 (TH012) promoter were also observed in both the H2B promoters. A gel mobility shift assay indicated that the hexamer and hexamer-like motifs bound the wheat bZIP proteins HBP-1a and/or HBP-1b in vitro. A novel sequence motif, (A/T)(G/A)AAAT(A/G), was found downstream of a translational stop codon as observed in several plant histone H2B cDNAs. Promoter activity was analyzed with H2B promoter-GUS fusion genes in the transient system using tobacco protoplasts. Studies of the promoter function in transgenic tobacco plants showed that the H2B promoters were preferentially active in meristematic tissues. Taken together, our data indicate that the H2B genes are regulated, in part, by the same mechanism as found in H3 and H4 gene transcription.
Plant Mol Biol 1995 Apr
PMID:Structural and functional characterization of two wheat histone H2B promoters. 778 80


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