Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: HUMANGGP:012675 (S100)
 6,012 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To understand better the mechanisms involved in the transduction of a calcium signal into an intracellular response via multiple calcium-modulated proteins, we have examined the calcium-modulated proteins, S100 and calmodulin, and their intracellular targets in rat C6 glioma cells. Subconfluent, confluent, and postconfluent C6 cells contain predominantly, if not exclusively, the S100 beta polypeptide. The level of S100 beta in C6 cells increases approximately 20-fold from subconfluency to postconfluency whereas the level of calmodulin increases only about two-fold. The subcellular distribution of S100 beta and calmodulin in mitotic cells is similar. However, the subcellular distribution of these proteins in interphase cells is different and appears to change with cell density. Gel overlay analysis demonstrated that the S100- and calmodulin-binding protein profiles are significantly different and that some of the binding proteins appear to change in intensity with cell density. These data demonstrate that S100 beta is the predominant S100 polypeptide in C6 cells and suggest that changes in S100 beta and S100 beta-binding proteins may be involved in regulating S100-mediated intracellular processes in C6 cells. Our studies also suggest that the levels of S100 and calmodulin may be differentially regulated in C6 cells.
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PMID:Levels and distribution of the calcium-modulated proteins S100 and calmodulin in rat C6 glioma cells. 327 41

In this paper we report the biochemical characterization of calgranulin C, a new member of the S100 protein family. The protein is highly abundant in the cytosol of pig granulocytes, with relatively small amounts in lymphocytes. A simple protocol for the rapid purification of calgranulin C is described. The purified protein migrates as a single entity on SDS-polyacrylamide gel electrophoresis while it has two isoforms focusing at pH 5.8 and 5.5. Gel filtration and cross-linking experiments indicate that calgranulin C is capable of dimerization. The complete amino acid sequence was determined by Edman degradation of peptides generated by trypsin and V8 protease digestion. Calgranulin C consists of 91 residues and has a calculated molecular mass of 10,614 daltons. This value is virtually identical to that obtained by electrospray mass spectrometry. Sequence analysis predicts two EF-hand calcium-binding motifs, the first having an extended loop that is distinctive of the S100 protein family. The metal-binding properties were studied by means of a direct 45Ca(2+)-binding assay and by tyrosine fluorescence titration. Calgranulin C binds not only calcium but also zinc ions. A single high affinity Zn(2+)-binding site per monomer was evidenced by fluorimetric titration. Zinc binding to calgranulin C induces a remarkable increase in the protein affinity for calcium; in the absence of zinc, the protein binds 1 Ca2+/monomer with a binding constant of about 2 x 10(4) M-1, whereas the Zn(2+)-loaded form binds 2 Ca2+/monomer with Ka values of approximately 3 x 10(7) and 6 x 10(4) M-1. Circular dichroism analysis showed that the binding of calcium to calgranulin C induces a 15% decrease in the apparent alpha-helix content. This result and the calcium-dependent binding of the protein to a phenyl-Superose column strongly suggest that calgranulin C undergoes a gross conformational change upon calcium binding, thus supporting the idea that this protein may be involved in Ca(2+)-dependent signal transduction events.
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PMID:Primary structure and binding properties of calgranulin C, a novel S100-like calcium-binding protein from pig granulocytes. 796 55

Replication of linear single-stranded parvovirus DNA proceeds by a rolling-hairpin mechanism which generates long, palindromic, duplex concatamers. Processing to monomer length requires initiation from origins of DNA replication located at the 3' and 5' ends of each embedded monomer, reactions which can be recapitulated in vitro for minute virus of mice (MVM). To determine which cellular proteins were essential for replication from these origins, S100 extracts from 293S cells were fractionated on phosphocellulose. When recombined, these fractions were able to support replication in vitro, dependent on the viral initiator protein NS1, using plasmid forms of the 5' origin or the minimal 3' origin as templates. Fraction P-cell 1 contains two factors, replication protein A (RPA) and proliferating-cell nuclear antigen (PCNA), known to be essential for simian virus 40 replication in vitro. When P-cell 1 was replaced with purified recombinant RPA and PCNA, NS1-mediated MVM replication initiated from the 5' origin but not from the 3' origin. The 3' origin is a 50-bp sequence containing three distinct recognition elements, an NS1 binding site, a site at which NS1 nicks the DNA to generate the priming 3' OH, and a region containing a consensus activated transcription factor (ATF) binding site. To identify the missing factor(s) for 3' origin replication, P-cell 1 was fractionated by further chromatography and active fractions were identified by their ability to complement RPA, PCNA, and P-cell 2 for NS1-mediated, origin-specific replication. Gel shift and UV cross-linking analysis of the replication-competent fractions revealed a novel 110-kDa sequence-specific DNA binding protein which recognized the consensus ATF binding site region of the origin and which we have termed parvovirus initiation factor, or PIF. Binding of PIF appears to activate the endonuclease function of NS1, allowing efficient and specific nicking of the 3' minimal origin under stringent conditions in vitro.
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PMID:A novel cellular site-specific DNA-binding protein cooperates with the viral NS1 polypeptide to initiate parvovirus DNA replication. 899 66

Calgizzarin is a Ca2+-binding protein of the S100 family that has been implicated in the regulation of cytoskeletal function through its Ca2+-dependent interaction with annexin I. The Ca2+-binding properties of calgizzarin (S100C) have not previously been thoroughly characterized. Calgizzarin, therefore, was purified from chicken gizzard smooth muscle by exploiting its Ca2+-dependent interaction with the hydrophobic matrix phenyl-Sepharose and is shown by 45Ca2+ overlay to bind Ca2+ more weakly than does calmodulin. Gel filtration in the absence and presence of Ca2+ suggested a dimeric structure of calgizzarin and indicated a more compact structure in the presence of Ca2+. Flow dialysis experiments indicated that, at physiological ionic strength, calgizzarin binds two Ca2+ ions per monomer (four per native dimer), as predicted from the deduced amino acid sequence which contains two putative EF-hands, with [Ca2+]0.5 of 0.52 mM and nH of 1.4 in the absence of Mg2+ and [Ca2+]0.5 of 0.3 mM and nH of 1.2 in the presence of 10 mM mgCl2. The hydrophobic fluorescent probe 2-p-toluidinylnaphthalene-6-sulphonate was used to demonstrate Ca(2+)-dependent exposure of a hydrophobic site(s) in calgizzarin. This approach also indicated the ability of calgizzarin to bind Zn2+. Interestingly, the affinity of calgizzarin for Ca2+ was enhanced approximately 10-fold in the presence of the hydrophobic probe, possibly reflecting an increased affinity for Ca2+ when calgizzarin binds to a target protein. Finally, the distribution of calgizzarin among chicken tissues was examined by immunoblotting: calgizzarin was expressed at its highest levels in lung tissue, followed by smooth muscle tissues (oesophagus, large intestine, trachea, and gizzard), kidney, liver, brain, and heart; it was not detected in small intestine or skeletal muscle.
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PMID:Characterization of the Ca2+-binding properties of calgizzarin (S100C) isolated from chicken gizzard smooth muscle. 901 77

Calcium receptor proteins are an essential link between hormones that alter intracellular calcium levels and the generation of cellular responses. However, there is no information available regarding the role of calcium receptor proteins, in particular the S100 family, in insulin action and/or diabetes. This study examines the effects of streptozotocin-induced type I diabetes on the expression of the individual S100A1 and S100B isoforms as well as their binding proteins. Diabetes did not increase (or initiate) S100B expression in any non-S100B-expressing tissue (skeletal muscle, heart, kidney, liver, spleen, and pancreas). In all S100B-expressing tissues examined (brain, white fat, and testes), S100B protein levels increased approximately 2-fold while steady state S100B messenger RNA (mRNA) levels decreased. S100A1-expressing tissues exhibited increased (kidney and lung), decreased (skeletal muscle), and unchanged (brain and heart) S100A1 protein levels. While noncoordinate changes in S100A1 protein and steady state mRNA levels were observed in heart, other S100A1-expressing tissues (brain, slow twitch skeletal muscle, and kidney) exhibited coordinate changes in S100A1 protein and steady state mRNA levels. Altogether, these results suggest that the effects of diabetes on S100 expression are isoform as well as tissue-specific. Gel overlay analysis of the S100-binding protein profile revealed both increases and decreases in binding proteins in all tissues examined. In summary, changes in the expression of S100A1, S100B, and S100-binding proteins occur in type I diabetes and represent important molecular events in the effects of insulin/insulin insufficiency on cell function.
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PMID:S100A1 and S100B expression and target proteins in type I diabetes. 938 98

The 3' noncoding region (NCR) of the negative-strand RNA [3'(-)NCR RNA] of the arterivirus simian hemorrhagic fever virus (SHFV) is 209 nucleotides (nt) in length. Since this 3' region, designated 3'(-)209, is the site of initiation of full-length positive-strand RNA and is the template for the synthesis of the 5' leader sequence, which is found on both full-length and subgenomic mRNAs, it is likely to contain cis-acting signals for RNA synthesis and to interact with cellular and viral proteins to form replication complexes. Gel mobility shift assays showed that cellular proteins in MA104 S100 cytoplasmic extracts formed two complexes with the SHFV 3'(-)209 RNA, and results from competition gel mobility shift assays demonstrated that these interactions were specific. Four proteins with molecular masses of 103, 86, 55, and 36 kDa were detected in UV-induced cross-linking assays, and three of these proteins (103, 55, and 36 kDa) were also detected by Northwestern blotting assays. Identical gel mobility shift and UV-induced cross-linking patterns were obtained with uninfected and SHFV-infected extracts, indicating that the four proteins detected are cellular, not viral, proteins. The binding sites for the four cellular proteins were mapped to the region between nt 117 and 184 (68-nt sequence) from the 3' end of the SHFV negative-strand RNA. This 68-nt sequence was predicted to form two stem-loops, SL4 and SL5. The 3'(-)NCR RNA of another arterivirus, lactate dehydrogenase-elevating virus C (LDV-C), competed with the SHFV 3'(-)209 RNA in competition gel mobility shift assays. UV-induced cross-linking assays showed that four MA104 cellular proteins with the same molecular masses as those that bind to the SHFV 3'(-)209 RNA also bind to the LDV-C 3'(-)NCR RNA and equine arteritis virus 3'(-)NCR RNA. However, each of these viral RNAs also bound to an additional MA104 protein. The binding sites for the MA104 cellular proteins were shown to be located in similar positions in the LDV-C 3'(-)NCR and SHFV 3'(-)209 RNAs. These data suggest that the binding sites for a set of the cellular proteins are conserved in all arterivirus RNAs and that these cell proteins may be utilized as components of viral replication complexes.
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PMID:A 68-nucleotide sequence within the 3' noncoding region of simian hemorrhagic fever virus negative-strand RNA binds to four MA104 cell proteins. 955 24

MCS4 RNA (125 nt in length) is one of the small stable RNAs found in Mycoplasma capricolum cells. Gel shift assay was performed with the 5' end-32P-labeled MCS4 RNA and the S100 fraction from M. capricolum to identify the RNA binding proteins. Several bands were detected above free MCS4 RNA, indicating that the RNA formed complexes with proteins and/or RNAs. One of the proteins which specifically binds to MCS4 RNA was purified. The amino acid sequence of the N-terminus revealed 60 to 80% identity to those of glyceraldehyde-3-phosphate dehydrogenases (GAPDH) from various sources.
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PMID:Purification of a Mycoplasma capricolum MCS4 RNA binding protein and cloning its gene. 958 62

The FSP1 gene encodes a filament-binding S100 protein with paired EF hands that is specifically expressed in fibroblasts. This led us to look for cis-acting elements in the FSP1 promoter that might engage nuclear transcription factors unique to fibroblasts. The first exon of FSP1 is noncoding, therefore, a series of luciferase reporter minigenes were created containing varying lengths of 5'-flanking sequence, the first intron, and the noncoding region of the second exon. A position and promoter-dependent proximal element between -187 and -88 bp was shown to be active in fibroblasts but not in epithelium. Sequence in the first intron from +777 to +964 had an enhancing effect that was not cell type specific. Hsv TK reporter constructs driven by this promoter/intron cassette in transgenic mice were coexpressed appropriately with FSP1 in tissue fibroblasts. Gel mobility shift competitor assays identified a novel domain, FTS-1 (fibroblast transcription site-1; TTGAT from -177 to -173 bp), that specifically interacts with nuclear extracts from fibroblasts. The necessity of this binding site was confirmed by site-specific mutagenesis. Database searches also turned up putative FTS-1 sites in the early promoter regions of other fibroblast expressed proteins, including the alpha1 and alpha2(I), and alpha1(III) collagens and the alphaSM-actin gene. We hypothesize that the selective engagement of FTS-1 elements may contribute to the mesenchymal phenotype of fibroblasts and perhaps other dedifferentiated cells.
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PMID:Identification of a novel cis-acting element for fibroblast-specific transcription of the FSP1 gene. 969 Oct 22

The potential role of RNA processing in regulating neurofilament (NF) subunit expression and in mediating the neuropathic effects of NF transgenes was explored by determining whether similar regulatory elements and cognate binding factors are present in NF mRNAs. Gel-shift studies were used to compare RNA-binding complexes that assemble on the 3'UTR of the heavy (NF-H), mid-sized (NF-M) and light (NF-L) NF mRNAs when radioactive RNA probes are incubated with high-speed supernatants (S100) of rat brain homogenates. RNA-binding complexes were characterized by their rate of migration in non-denaturing gels and by their ability to be competed with specific homoribopolymers. Similar RNA-binding complexes formed on probes to the 3'UTRs of NF-L and NF-H mRNAs. The complexes were competed with poly(C) and are referred to as poly(C)-sensitive complexes. Their binding sites were localized to a 36 nt sequence in the mid-distal region of the NF-H 3'UTR and to a 45 nt sequence at the proximal edge of the 3'UTR of the NF-L transcript. Although the binding sites showed limited sequence homology, the complexes were cross-competed with unlabeled probes and radioactivity in either probe was cross-linked to a 43 kDa protein. The 43 kDa protein also bound directly to NF-L and NF-H probes in Northwestern blots. Functional studies showed that deletion of the binding sites markedly increased expression of a luciferase reporter gene containing the 3'UTR of NF-L or NF-H by stabilizing the fusion transcripts. Point mutations in the NF-H binding site which prevented formation of the poly(C)-sensitive complex also stabilized the fusion mRNA. The findings reveal a common destabilizing element in the 3'UTR of NF-L and NF-H mRNAs that may be important in coordinating NF subunit expression and in mediating the neuropathic effects of the NF-L and NF-H transgenes in transgenic mice.
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PMID:Similar poly(C)-sensitive RNA-binding complexes regulate the stability of the heavy and light neurofilament mRNAs. 1083 25

Nuclear mRNAs in trypanosomatids are generated by trans-splicing. Although trans-splicing resembles cis-splicing in many ways and most of the U RNA participants have been characterized, relatively few involved proteins have been identified. Herein, we employed a yeast three-hybrid system to identify a protein, XB1, which binds to the Trypanosoma cruzi SL RNA. XB1 is a approximately 45 kDa protein which is homologous to the essential pre-mRNA-splicing factor PRP31p from Saccharomyces cerevisiae. Gel shift assays and UV cross-linking experiments with recombinant XB1 confirmed that this T. cruzi protein binds the SL RNA in vitro. The binding site of XB1 on the SL RNA was mapped to stem-loop II by deletion of the SL RNA 'bait' in the three-hybrid system. Finally, UV cross-linking SL RNA with S100 extract indicated native XB1 protein and SL RNA interaction in T. cruzi extract.
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PMID:Identification of a spliced leader RNA binding protein from Trypanosoma cruzi. 1116 85


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