Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Effects of melittin, an amphipathic polypeptide, on various species of protein kinases were investigated. It was found that melittin inhibited the newly identified phospholipid-sensitive Ca2+-dependent protein kinase (from heart, brain, spleen and neutrophils) and the cardiac myosin light-chain kinase, a calmodulin-sensitive Ca2+-dependent enzyme. In contrast, melittin had little or no effect on either the holoenzymes of the cardiac cyclic AMP-dependent and cyclic GMP-dependent protein kinases or the catalytic subunit of the former. Kinetic analysis indicated that melittin inhibited phospholipid-sensitive Ca2+-dependent protein kinase non-competitively with respect to ATP (Ki = 1.3 microM); although exhibiting complex kinetics, its inhibition of the enzyme was overcome by phosphatidylserine (a phospholipid cofactor), but not by protein substrate (histone H1) or Ca2+. On the other hand, melittin inhibited myosin light-chain kinase non-competitively with respect to ATP (Ki = 1.4 microM) or Ca2+ (Ki = 1.9 microM), and competitively with respect to calmodulin (Ki = 0.08 microM); although exhibiting complex kinetics, its inhibition of the enzyme was reversed by myosin light chains (substrate protein). The present findings indicate the presence of functionally important hydrophobic or hydrophilic loci on the Ca2+-dependent protein kinases, but not on the cyclic nucleotide-dependent class of protein kinase, with which melittin can interact. Moreover, the kinetic data suggest that melittin inhibited myosin light-chain kinase by interacting with a site on the enzyme the same as, or proximal to, the calmodulin-binding site, thus interfering with the formation of active enzyme-calmodulin-Ca2+ complex.
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PMID:Inhibition by melittin of phospholipid-sensitive and calmodulin-sensitive Ca2+-dependent protein kinases. 689 76

The structure of histone H1 and wheat embryos and calf thymus was compared in fragments formed via oxidative splitting of the tyrosine residues of the polypeptide chain. It was shown that the protein under study is structurally similar to histone H1 from calf thymus in some parameters, e. g. asymetry of the basic amino acid residues, predominantly in the C-terminal protein moiety; localization of the tyrosine residues in the N-terminal part of the molecule. The structural specificity of histone H1 from wheat embryos consists in the approximation of histidine and tyrosine residues.
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PMID:[Localization of tyrosine residues in histone H1 from wheat embryos]. 724 71

A comparison of human and calf thymus extracts was carried out. The thymus extracts and the fractions isolated from them differ in their physico-chemical properties, amino acid composition and biological activity. The extracts tested contain different amounts of the thymus factor, which stimulates the reactions of cellular and humoral immunity. The results obtained suggests that calf and human thymus contain only one immunomodulating factor, namely thymarin, a component of thymus extracts from various sources, in particular of thymosin. In some of its physico-chemical properties thymarin is similar to histone H1 from calf thymus, thus suggesting an essential role of this histone in the formation and differentiation of T-lymphocytes. A possibility of quantitative estimation and identification of the immunomodulating polypeptide in thymus extracts obtained by various methods is postulated.
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PMID:[Isolation, purification and identification of an immunomodulating polypeptide from human and calf thymus]. 729 26

The primary structure of sperm histone H1Parechinus has been determined. H1Parechinus consists of a polypeptide chain of the following 248 amino acid residues: Pro-Gly-Ser-Pro-Gln-Lys-Arg-Ala-Ala-Ser-Pro-Arg-Lys-Ser-Pro-Arg-Lys-Ser-Pro-Lys-Lys-Ser-Pro-Arg-Lys-Ala-Ser-Ala-Ser-Pro-Arg-Arg-Lys-Ala-Lys-Arg-Ala-Arg-Ala-Ser-Thr-His-Pro-Pro-Val-Leu-Glu-Met-Val-Gln-Ala-Ala-Ile-Thr-Ala-Met-Lys-Glu-Arg-Lys-Gly-Ser-Ser-Ala-Ala-Lys-Ile-Lys-Ser-Tyr-Met-Ala-Ala-Asn-Tyr-Arg-Val-Asp-Met-Asn-Val-Leu-Ala-Pro-His-Val-Arg-Arg-Ala-Leu-Arg-Asn-Gly-Val-Ala-Ser-Gly-Ala-Leu-Lys-Gln-Val-Thr-Gly-Thr-Gly-Ala-Ser-Gly-Arg-Phe-Arg-Val-Gly-Ala-Val-Ala-Lys-Pro-Lys-Lys-Ala-Lys-Lys-Thr-Ser-Ala-Ala-Ala-Lys-Ala-Lys-Lys-Ala-Lys-Ala-Ala-Ala-Ala-Lys-Lys-Ala-Arg-Arg-leads to Lys-Ala-Lys-Ala-Ala-Ala-Lys-Arg-Lys-Ala-Ala-Leu-Ala-Lys-Lys-Lys-Ala-Ala-Ala-Ala-Lys-Arg-Lys-Ala-Ala-Ala-Lys-Ala-Lys-Lys-Ala-Lys-Lys-Pro-Lys-Lys-Lys-Ala-Ala-Ala-Lys-Lys-Ala-Lys-Lys-Pro-Ala-Lys-Lys-Ser-Pro-Lys-Lys-Ala-Lys-Lys-Pro-Ala-Lys-Lys-Ser-Pro-Lys-Lys-Lys-Lys-Ala-Lys-Arg-Ser-Pro-Lys-Lys-Ala-Lys-Lys-Ala-Ala-Gly-Lys-Arg-Lys-Pro-Ala-Ala-Lys-Lys-Ala-Arg-Arg-Ser-Pro-Arg-Lys-Ala-Gly-Lys-Arg-Arg-Ser-Pro-Lys-Lys-Ala-Arg-Lys. The protein consists of three domains. Compared to other H1 and H5 histones, there is a very similar hydrophobic central domain and the carboxyl-terminal domain is very rich in lysine and alanine. H1Parechinus is similar to H5 histones in that the carboxyl-terminal domain also contains many arginine residues close to the carboxyl terminus. The carboxyl-terminal domain of H1Parechinus appears to have been constructed by a series of variable duplications. The amino-terminal domain of H1Parechinus is longer and quire different to that of other H1 and H5 histones and is characterized by a repeating tetrapeptide of the general type Ser-Pro-(basic)2. The known sequence of a histone H1 gene from Psammechinus miliaris [Schaffner, W. et al. (1978) Cell, 14, 655-671] is compared to the sequence of H1Parechinus. Again the central hydrophobic domains are similar whereas the amino terminal domains are very different. The functions of the various domains of sperm histone H1Parechinus are discussed.
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PMID:The primary structure of histone H1 from sperm of the sea urchin Parechinus angulosus. 2. Sequence of the C-terminal CNBr peptide and the entire primary structure. 736 5

A soluble protein kinase purified from winged bean (Psophocarpus tetragonolobus) shoots, has been assessed as a monomeric enzyme with an approximate M(r) of 60,000 in spite of the presence of two polypeptides of 61 and 58 kDa determined by SDS/PAGE. Immunoblot analyses using either of the two antisera raised individually against the polypeptides, detect both of them in purified preparations and a single larger polypeptide (62 kDa) in freshly prepared tissue homogenates, clearly indicating the likelihood of the doublet being formed from the larger one by proteolysis. Histone H1, syntide 2 and a synthetic myosin light chain-related peptide (MLC-peptide) have been identified as exogenous substrates of the enzyme. Complete Ca(2+)-dependence for substrate phosphorylation, a drastic inhibition of the reaction by a calmodulin (CaM) antagonist which can be partially reversed by a heterologous CaM and direct 45Ca(2+)-binding on blot, form compelling evidence in favour of a CaM-like domain of the enzyme. Both the polypeptides of the purified enzyme undergo intramolecular autophosphorylation on serine residue(s). Unlike the substrate phosphorylation reaction, autophosphorylation is Ca(2+)-independent and is not inhibited by the CaM antagonist. Down-regulation of substrate phosphorylation by auto-phosphorylation, and stimulation of the autophosphorylation by histone H1 and MLC-peptide, are novel regulatory features of the enzyme.
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PMID:Characterization of a winged bean (Psophocarpus tetragonolobus) protein kinase with calmodulin-like domain: regulation by autophosphorylation. 782 30

Cellular proteins extracted from normal and cancer cells bind polymerizing ADP-ribose transferase (pADPRT) on nitrocellulose membrane transblots. Histones at 1 mg/ml concentration completely prevent the binding of pADPRT to cellular proteins, indicating that the binding of histones to pADPRT sites competitively blocks the association of pADPRT to proteins other than histones. The direct binding of pADPRT to histones is shown by cross-linking with glutaraldehyde. The COOH-terminal basic histone H1 tail binds to the basic polypeptide domain of pADPRT. The basic domain present in the NH2-terminal part of core histones is the probable common structural feature of all core histones that accounts for their binding to pADPRT. Two polypeptide domains of pADPRT were identified, by way of CNBr fragments, to bind histones. These two domains are located within the 64-kDa fragment of pADPRT and are contiguous with the polypeptide domains that were shown to participate in self-association of pADPRT, ending at the 606th amino acid residue. The polypeptide domains of pADPRT which participate in DNA binding are thus shown to associate also with other proteins. Intact pADPRT binds to both the zinc-free or zinc-reconstituted basic polypeptide fragments of pADPRT. Histones activate auto-poly(ADP)-ribosylation of pADPRT by increasing the number of short oligomers on pADPRT. This reaction is also dependent in a biphasic manner on the concentration of pADPRT. Histones in solution are only marginally poly(ADP)-ribosylated but are good polymer acceptors when incorporated into artificial nucleosome structures.
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PMID:Identification of domains of poly(ADP-ribose) polymerase for protein binding and self-association. 785 24

Stage-specific activator protein (SSAP) is a 43-kDa polypeptide that binds to an enhancer element of the sea urchin late histone H1 gene. This enhancer element mediates the transcriptional activation of the late histone H1 gene in a temporally specific manner at the mid-blastula stage of embryogenesis. We have cloned cDNAs encoding SSAP by using polyclonal antibodies raised against purified SSAP to screen expression libraries. SSAP is unrelated to previously characterized transcription factors; however, it exhibits striking homology to a large family of proteins involved in RNA processing. The protein is a sequence-specific DNA-binding protein that recognizes both single- and double-stranded DNA. The DNA-binding domain of the protein was localized to the conserved RNA recognition motif (RRM). In addition to tandem copies of this conserved domain, SSAP contains a central domain that is rich in glutamine and glycine and a C-terminal domain that is enriched in serine, threonine, and basic amino acids. Overexpression of SSAP in sea urchin embryos by microinjection of either synthetic mRNA or an SSAP expression vector results in four- to eightfold transactivation of target reporter genes that contain the enhancer sequence. Transactivation occurs beginning only at the mid-blastula stage of development, suggesting that SSAP must be modified in a stage-specific manner in order to activate transcription. In addition, there are a number of other RRM-containing proteins that contain glutamine-rich regions which are postulated to function in the regulation of RNA processing. Instead, we suggest that SSAP is a member of a family of glutamine-rich RRM proteins which constitute a novel class of transcription factors.
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PMID:The embryonic enhancer-binding protein SSAP contains a novel DNA-binding domain which has homology to several RNA-binding proteins. 786 19

The complete nucleotide sequence of rice dwarf phytoreovirus genome segment 2 (S2) was determined to be 3,512 nucleotides long with one open reading frame initiating at nucleotide 15 and terminating at nucleotide 3363. The encoded polypeptide was predicted to have 1,116 residues with a relative molecular weight of 123 kD. Comparison of S2 of two isolates showed they had identical lengths and 97 and 98.3% nucleotide and amino acid sequence identities, respectively. A search of the Swiss-Prot data base (R 22.0) failed to find any proteins with significant homology to the S2-encoded protein. Determination of the nucleotide sequence of the S2 has completed the sequence determination of the genome of rice dwarf virus. Homology searches made for proteins encoded by each of the genomic segments showed that the polypeptide encoded by S11 has similarity to histone H1 protein and VP6 of blue tongue virus, indicating it might possess nucleic acid binding properties.
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PMID:Nucleotide sequence of rice dwarf phytoreovirus genome segment 2: completion of sequence analyses of rice dwarf virus. 792 90

Proteolysis of rat liver chromatin by the Arg-C peptidase, clostripain, is characterized by a progressive fragmentation of the N-terminal segments of the four core histones H2A, H2B, H3 and H4, until a well-defined limit digest is reached. This work addresses the case of histone H4. Two intermediate proteolytic sites are identified for this histone, i.e. Arg3 and Arg17, before the limit digest is achieved through cleavage of the polypeptide chain after Arg19. The accessibility of these intermediate sites depends strongly on the presence or absence of histone H1. When H1 is absent, both intermediate sites of histone H4 are similarly accessible, whereas one of them, Arg3, becomes totally inaccessible in the presence of histone H1. Di- and trinucleosomes were used with the aim of avoiding any interference with superstructural effects which can occur with longer polynucleosomes in the presence of H1. We also investigated the accessibility of the Arg sites of H1 that are located primarily in the central globular domain of this histone. In free histone H1, all the centrally located Arg sites are accessible to clostripain. In contrast, in the chromatin-bound state none of these sites is accessible. Besides the arginyl sites in the central globular domain of H1, two Arg residues are observed with the most abundant H1d variant in rat chromatin, one in the N-terminal region and the other in the C-terminal region. The restricted number of proteolytic fragments observed with chromatin-bound H1 is accounted for by the cleavage of H1 after these Arg residues located on the outside of the globular domain. Our results suggest that mutual steric effects are at play between histones H1 and H4 and indicate that the N termini of both histones H4 in the nucleosome lie in close proximity to the globular domain of H1. Based on these observations and taking into account the known structural features of the nucleosome, we propose a model for positioning the N-terminal segments of both histones H4 at the periphery of the nucleoprotein structure. In this model both H4 segments are located within the expanded DNA minor grooves, at periods +/- 1, symmetrically disposed relatively to the nucleosome dyad axis. This arrangement brings the amino ends of both H4 molecules in close contact with the H1 globular domain thus accounting for the observed inaccessibility of the Arg3 site of H4 in the presence of H1.
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PMID:Evidence indicating proximity in the nucleosome between the histone H4 N termini and the globular domain of histone H1. 793 40

H1TF2 is a CCAAT transcription factor that binds to the histone H1 subtype-specific consensus sequence, which has previously been shown to be necessary for temporal regulation of histone H1 transcription during the cell cycle (F. La Bella, P. Gallinari, J. McKinney, and N. Heintz, Genes Dev. 3:1982-1990, 1989). In this study, we report that H1TF2 is a heteromeric CCAAT-binding protein composed of two polypeptide doublets of 33 and 34 kDa and 43 and 44 kDa that are not antigenically related. The 33- and 34-kDa species were not detected in our previous studies (P. Gallinari, F. La Bella, and N. Heintz, Mol. Cell. Biol. 9:1566-1575, 1989) because of technical problems in detection of these heavily glycosylated subunits. The cloning of H1TF2A, the large subunit of this factor, reveals it to be a glutamine-rich protein with extremely limited similarity to previously cloned CCAAT-binding proteins. A monospecific antiserum produced against bacterially synthesized H1TF2A was used to establish that HeLa cell H1TF2A is phosphorylated in vivo and that, in contrast to the H2b transcription factor Oct1 (S. B. Roberts, N. Segil, and N. Heintz, Science 253:1022-1026, 1991; N. Segil, S. B. Roberts, and N. Heintz, Cold Spring Harbor Symp. Quant. Biol. 56:285-292, 1991), no gross change in H1TF2A phosphorylation is evident during the cell cycle. Further immunoprecipitation studies demonstrated that H1TF2 is heterodimeric in the absence of DNA in vivo and identified several H1TF2-interacting proteins that may play a role in H1TF2 function in vivo.
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PMID:H1TF2A, the large subunit of a heterodimeric, glutamine-rich CCAAT-binding transcription factor involved in histone H1 cell cycle regulation. 796 68


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