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Results for “S100 Calcium Binding Protein beta Subunit”

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PubMed1984

Immunohistochemical study on the distribution of alpha and beta subunits of S-100 protein in human neoplasm and normal tissues.

The immunohistochemical distribution and localization of the alpha and beta subunits of S-100 protein in human neoplasms and normal tissues were studied by the PAP method using monospecific rabbit antibodies against each subunit. Beta subunit immunoreactivity was detected in all S-100-positive cells and tumors reported previously. In contrast alpha subunit immunoreactivity was absent from Schwann cells, schwannomas, neurofibromas, granular cell myoblastomas, pituicytes of the neurohypophysis, Langerhans cells, interdigitating reticulum cells, and histiocytosis X cells. Interestingly, only the alpha subunit was detected in neurons of both central and peripheral nervous system, and in lymph node macrophages. Human S-100-positive cells are divided into three groups; the first is composed of cells containing only the beta subunit (probably S-100b; beta beta), the second consists of cells containing both the alpha and beta subunits, and the third is composed of cells containing only the alpha subunit (probably S- 100ao ; alpha alpha). The ontogentic relationships between S-100-positive cells and tumors are discussed in the light of these findings.

Biomarkers↗

PubMed1985

S-100 alpha-like immunoreactivity in tubules of rat kidney. A clue to the function of a "brain-specific" protein.

The localization of the alpha and beta subunits of S-100 protein was studied in normal tissue where the identification of three subclasses of S-100 containing cells was derived: i) cells that contain both alpha and beta subunits; ii) cells that contain only the alpha subunit; and iii) cells that contain only the beta subunit. In this study monospecific antibodies against the S-100 alpha and beta subunits were used to characterize the S-100-like immunoreactivity in the rat kidney: Certain cells in the distal nephron, i.e., the connecting piece, collecting ducts, and the thin limb of Henle's loop, contained S-100 alpha immunoreactivity. Proximal tubules, the thick ascending limb of Henle's loop, the distal tubules, and the juxtaglomerular apparatus were negative. No S-100 beta immunoreactivity was found in kidney tubules. However, Schwann cells of renal pelvic nerves contained S-100 beta immunoreactivity. The presence of S-100 alpha antigen in certain cells of the kidney gives further support to the assumption that the alpha subunit of S-100a is related to cells that are highly involved in pH, electrolyte, and water regulation.

Animals↗

PubMed2006

Specific changes in levels of autoantibodies to glutamate and opiate receptors induced by morphine administration in rats.

Several groups of brain receptors are involved in the mechanisms underlying the development of opiate addiction, but the interactions occurring between these neuroreceptors and the immune system, including potential autoimmune responses, remain poorly understood. We studied in rats the effects of repeated administration of different psychotropic drugs on serum levels of autoantibodies (aAbs) to the mu delta-opiate receptor (MDOR), as well as to the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) GluR1 and to the N-methyl-D-aspartate (NMDA) NR2 subunits of the glutamate receptor, as analyzed by ELISA. We found that repeated administration of morphine significantly elevated aAbs levels to MDOR and to the AMPA GluR1 subunit, but not to the NMDA NR2 subunit. In contrast, a similar regimen of a psychostimulant drug, such as D-amphetamine, or a commonly abused substance, such as nicotine, had no effect on these aAbs levels. A nonspecific elevating effect on aAbs to the brain structural protein S100B was observed for all drugs tested versus controls. These observations support the hypothesis that, following opiate administration, specific interactions between nervous and immune systems occur. Therefore, together with further investigations on their potential functional consequences, we propose a thorough exploration of aAbs to MDOR and to AMPA GluR1 subunit as early biomarkers signaling opiate addiction.

Animals↗

PubMed2002

Utility of immunostaining for S-100 protein subunits in gonadal sex cord-stromal tumors, with emphasis on the large-cell calcifying Sertoli cell tumor of the testis.

This study concerns the immunohistochemical localization of S-100 alpha, S-100 beta, and whole brain S-100 (wbS-100) in testicular large-cell calcifying Sertoli cell tumor (LCCSCT). We examined 8 LCCSCTs (7 benign and 1 malignant), 6 Sertoli cell tumors not otherwise specified (SCTs-NOS), 6 Leydig cell tumors (LCTs), 5 ovarian Sertoli-Leydig cell tumors (SLCTs), and 7 gonadoblastomas (GBLs). The 8 LCCSCTs showed immunoreactivity for S-100 alpha, S-100 beta, and wbS-100. Five of the 6 LCTs and the Leydig cell components in the ovarian SLCTs stained positively for S-100 alpha and wbS-100 but were negative for S-100 beta. SCTs-NOS and the Sertoli cell components in the SLCTs occasionally showed focal and weak/moderate positivity for S-100 alpha, S-100 beta, and wbS-100. Sex cord cells of the GBLs were positive for S-100 beta and wbS-100 and negative for S-100 alpha. Germ cell elements of the GBLs were negative for S-100 alpha, S-100 beta, and wbS-100. In nonneoplastic testicular parenchyma adjacent to the above-mentioned tumors, there was S-100 alpha reactivity in Leydig cells, rete testis, and a few Sertoli cells. S-100 beta reactivity was seen in a few Sertoli cells, Schwann cells, and some endothelial cells. WbS-100 reactivity was present in Leydig cells, a few Sertoli cells, rete testis, Schwann cells, and some endothelial cells. The results indicate that S-100 alpha and S-100 beta can potentially be used as immunohistochemical markers for LCCSCT, especially when differentiating it from LCT, which may mimic LCCSCT on routine histopathology. Although the biological significance of both S-100 subunits expression in LCCSCT remains unknown, these notable calcium-binding proteins may be associated with the characteristic calcification in LCCSCT through regulation of calcium levels in the tumor cells.

Biomarkers↗

PubMed1983

A rapid separation of S100 subunits by high performance liquid chromatography: the subunit compositions of S100 proteins.

The subunits of S100 protein were dissociated and separated from each other by high performance liquid chromatography on a macroreticular poly-styrene resin, using an acetonitrile-trifluoroacetic acid solvent system. The separation was completed within 80 min in monitoring the effluent at 210 and 280 nm, allowing a rapid and sensitive identification of each S100 protein in terms of subunit composition, and a simultaneous purification of subunits. The method enabled to estimate the subunit compositions of S100a, S100b, and S100a0 protein purified from bovine brain, and revealed a micro-heterogeneity of S100 subunits as applied to the mixtures of S100 protein prepared from bovine, human and rat brain.

Amino Acids↗

PubMed1995

Characterization of S-100b binding epitopes. Identification of a novel target, the actin capping protein, CapZ.

Short amino acid sequences that interact with the Ca2+ binding protein S-100b were identified by screening a bacteriophage random peptide display library. S-100b binding bacteriophages were selected by Ca(2+)-dependent affinity chromatography, and the sequence of the random peptide insert contained in 51 clones was determined. Alignment of the sequence of 44 unique S-100b binding peptides identified a common motif of eight amino acids. A subgroup of peptides that contained sequences with the highest degree of similarity had the consensus motif (K/R)(L/I)XWXXIL, in which predominantly P, S, and N were found in position 3, and S and D were found in position 5. Analysis of sequence databanks identified a similar sequence in the COOH-terminal region of the alpha-subunit of actin capping proteins. The peptide TRTKIDWNKILS (TRTK-12), corresponding to the region of greatest homology within this region of the subunit of actin capping proteins (e.g. amino acids 265-276 in CapZ alpha 1 and CapZ alpha 2), was synthesized and shown by fluorescence spectrophotometry to bind S-100b in a Ca(2+)-dependent manner. Gel overlay and cross-linking experiments demonstrated the interaction of S-100b with CapZ to be Ca2+ dependent. Moreover, this interaction was blocked by addition of TRTK-12 peptide. These results identify Ca(2+)-dependent S-100b target sequence epitopes and designate the carboxyl terminus of the alpha-subunit of actin capping proteins, like CapZ, to be a target of S-100b activity. The high level of conservation within this region of actin capping proteins and the apparent high affinity of this interaction strongly suggest that the interaction between S-100b and the alpha-subunit of actin capping proteins is biologically significant.

Amino Acid Sequence↗

PubMed1997

Epithelial hyperplasia of usual type expresses both S100-alpha and S100-beta in a heterogeneous pattern but ductal carcinoma in situ can express only S100-alpha in a monotonous pattern.

Immunohistochemical identification of myoepithelial cells using alpha-smooth muscle actin provides little information about the nature of solid or quasi-solid portions of epithelial hyperplasia and ductal carcinoma in situ (DCIS) because actin-rich myoepithelial cells are usually demonstrated only in the stromal-epithelial junction of both lesions. We studied the differential distribution of alpha-subunit (S100-alpha) and beta-subunit (S100-beta) of S100 protein in actin-negative areas of usual epithelial hyperplasia and DCIS by employing the streptavidin method with monospecific rabbit antibodies against each subunit. All usual epithelial hyperplasias (n = 17) were composed of heterogeneous epithelial cell types; cells expressing S100-alpha and/or S100-beta were intermingled with non-expressing cells, resulting in a mosaic-like pattern. On the contrary, DCIS (n = 32) uniformly lacked immunoreactive S100-beta; S100-alpha was diffusely expressed in 24 (68.8%) DCIS (three solid/comedo, 13 cribriform, four endocrine, one micropapillary, three papillary variants) and negative in the remaining eight (31.2%) DCIS (one cribriform, two micropapillary, four papillary and one apocrine variants). In conclusion, in contrast to usual epithelial hyperplasia that expresses both S100-alpha and S100-beta in a heterogeneous pattern, DCIS can express only S100-alpha in a monotonous pattern, possibly signifying unidirectional differentiation toward secretory glandular epithelium.

Adult↗

PubMed2004

Capping protein binding to S100B: implications for the tentacle model for capping the actin filament barbed end.

S100B binds tightly to a 12-amino acid peptide derived from heterodimeric capping protein. In native intact capping protein, this sequence is in the C terminus of the alpha-subunit, which is important for capping the actin filament. This C-terminal region is proposed to act as a flexible "tentacle," extending away from the body of capping protein in order to bind actin. To this hypothesis, we analyzed the interaction between S100B and capping protein in solution. The C-terminal 28 amino acids of the alpha-subunit, the proposed tentacle, bound to S100B as a free synthetic peptide or a glutathione S-transferase fusion (K(d) approximately 0.4-1 microm). In contrast, S100B did not bind to whole native capping protein or functionally affect its capping activity. S100B does not bind, with any significant affinity, to the proposed alpha-tentacle sequence of whole native capping protein in solution. In the NMR structure of S100B complexed with the alpha-subunit-derived 12-amino acid peptide, the hydrophobic side of a short alpha-helix in the peptide, containing an important tryptophan residue, contacts S100B. In the x-ray structure of native capping protein, the corresponding sequence of the alpha-subunit C terminus, including Trp(271), interacts closely with the body of the protein. Therefore, our results suggest the alpha-subunit C terminus is not mobile as predicted by the tentacle model. Addition of non-ionic detergent allowed whole capping protein to bind weakly to S100B, indicating that the alpha-subunit C terminus can be mobilized from the surface of the capping protein molecule, presumably by weakening the hydrophobic binding at the contact site.

Actin Depolymerizing Factors↗

PubMed1998

Suppression of copper-induced cellular damage by copper sequestration with S100b protein.

We previously reported that S100b protein (homodimer of S100 beta subunit) can bind copper ions with a submicromolar dissociation constant (T. Nishikawa et al., J. Biol. Chem. 272, 23037-23041, 1997). In this study, a question was addressed as to whether this protein can sequester copper ions in an in vivo situation. Escherichia coli cells that had been rendered able to produce a fusion protein of rat S100 beta subunit with glutathione S-transferase displayed a marked resistance to cellular damage induced by copper alone or its combination with H2O2, compared with control cells expressing the transferase moiety only. A study by gel chromatography showed that about half of the expressed S100 beta fusion protein in the cytosol of copper-treated cells was eluted in the void volume fraction (molecular mass > 200 kDa), which contained most of the copper incorporated. The S100 beta fusion protein purified from the void volume fraction was found to contain 82% of the total copper in the fraction, while in a parallel experiment with the control cells, the glutathione S-transferase eluted in the void volume fraction contained only 18% of the total copper. Thus, it is clear that extraneously expressed S100b protein can acts as a "copper sink," thereby protecting E. coli cells from copper-induced cellular damage.

Calcium-Binding Proteins↗

PubMed1997

Identification and structural influence of a differentially modified N-terminal methionine in human S100b.

The calcium-binding protein S100b is a homodimer comprised of two identical 91-residue beta-subunits. Recombinant S100b is a heterogeneous protein, although the basis of this heterogeneity has not been established. We have used mass spectrometry and NMR spectroscopy to determine that heterogeneity in S100b arises from a mixture of formyl-S100b and desformyl-S100b when expressed in Escherichia coli. Reversed-phase HPLC purification of these two forms of S100b has allowed the differences in N-terminal composition to be used as a probe for tertiary contacts in the protein. The presence or absence of the N-terminal formyl group affected the chemical shifts of sequence neighboring residues and those in the linker of the protein (residues 40-43), indicating that these two regions are close in space.

Amino Acid Sequence↗

PubMed1998

Solution structure of calcium-bound rat S100B(betabeta) as determined by nuclear magnetic resonance spectroscopy,.

The three-dimensional structure of Ca2+-bound rat S100B(betabeta) has been determined using data from a series of two-dimensional (2D), three-dimensional (3D), and four-dimensional (4D) nuclear magnetic resonance (NMR) experiments. Each S100beta subunit (91 residues) contains four helixes (helix 1, E2-R20; helix 2, K29-N38; helix 3, Q50-D61; and helix 4, F70-A83) and one antiparallel beta-sheet (strand 1, K26-K28; and strand 2, E67-D69) which brings the normal and pseudo EF-hands together. As found previously for rat apo-S100B(betabeta) [Drohat, A. C., et al. (1996) Biochemistry 35, 11577-11588], helixes 1, 1', 4, and 4' associate to form an X-type four-helix bundle at the symmetric dimer interface. Additionally, Ca2+ binding does not significantly change the interhelical angle of helixes 1 and 2 in the pseudo EF-hand (apo, Omega1-2 = 132 +/- 4 degrees; and Ca2+-bound, Omega1-2 = 137 +/- 5 degrees). However, the interhelical angle of helixes 3 and 4 in the normal EF-hand (Omega3-4 = 106 +/- 4 degrees) changed significantly upon the addition of Ca2+ (DeltaOmega3-4 = 112 +/- 5 degrees) and is similar to that of the Ca2+-bound EF-hands in calbindin D9K, calmodulin, and troponin (84 degrees </= Omega </= 128 degrees). Further, the four helixes within each S100beta subunit form a splayed-type four-helix bundle (four perpendicular helixes) as observed in Ca2+-bound calbindin D9K. The large Ca2+-dependent conformational change involving helix 3 exposes a cleft, defined by residues in the hinge region, the C-terminal loop, and helix 3, which is absent in the apo structure. This surface on Ca2+-bound S100B(betabeta) is likely important for target protein binding.

Animals↗

PubMed2006

A multidisciplinary overview of cardiogenic shock.

Cardiogenic shock complicating acute myocardial infarction (AMI) is reviewed from multidisciplinary viewpoints encompassing both basic and clinical aspects. Insights into the absolute obligate aerobic nature of the heart which possesses neither facultative capability nor functional collateral channels, together with O2 diffusion gradients, mitochondrial O2 sensing and anaerobic ATP deficiencies, are described in some detail. Myocardial adaptive responses against energy crisis, termed the Pasteur Effect, and hypoxia inducible factor (HIF)-1 alpha are implicated for cardiomyocyte viability. Oncosis and/or lysosomal autophagy cause such overwhelming numbers (several billions) of cardiomyocyte death, virtually simultaneously following coronary thrombotic occlusion. Apoptosis is briefly described and cardiogenic shock is discussed in terms of the diagnostic criteria by MIRU, unique hemodynamic manifestations, infarct sizes and border zone extension, and potentially jeopardized myocardium in the remote areas. Reperfusion injury, i.e., reactive oxygen species (ROS), is noted as a double-edged sword. The importance of early revascularization by means of PCI, CABG, and IABP support is emphasized according to current guidelines. For innovative promise in the future, de novo development of collateral channels by growth factors and trials of stem cell implantation aimed at myocardial regeneration are introduced.

Adenosine Triphosphate↗

PubMed1999

The calcium-modulated proteins, S100A1 and S100B, as potential regulators of the dynamics of type III intermediate filaments.

The Ca2+-modulated, dimeric proteins of the EF-hand (helix-loop-helix) type, S100A1 and S100B, that have been shown to inhibit microtubule (MT) protein assembly and to promote MT disassembly, interact with the type III intermediate filament (IF) subunits, desmin and glial fibrillary acidic protein (GFAP), with a stoichiometry of 2 mol of IF subunit/mol of S100A1 or S100B dimer and an affinity of 0.5-1.0 microM in the presence of a few micromolar concentrations of Ca2+. Binding of S100A1 and S100B results in inhibition of desmin and GFAP assemblies into IFs and stimulation of the disassembly of preformed desmin and GFAP IFs. S100A1 and S100B interact with a stretch of residues in the N-terminal (head) domain of desmin and GFAP, thereby blocking the head-to-tail process of IF elongation. The C-terminal extension of S100A1 (and, likely, S100B) represents a critical part of the site that recognizes desmin and GFAP. S100B is localized to IFs within cells, suggesting that it might have a role in remodeling IFs upon elevation of cytosolic Ca2+ concentration by avoiding excess IF assembly and/or promoting IF disassembly in vivo. S100A1, that is not localized to IFs, might also play a role in the regulation of IF dynamics by binding to and sequestering unassembled IF subunits. Together, these observations suggest that S100A1 and S100B may be regarded as Ca2+-dependent regulators of the state of assembly of two important elements of the cytoskeleton, IFs and MTs, and, potentially, of MT- and IF-based activities.

Calcium↗

PubMed1984

Immunohistochemical localization and distribution of S-100 proteins in the human lymphoreticular system.

Immunohistochemical localization of S-100b protein and S-100ao protein in human lymphoreticular system was studied by using monospecific antibody directed against either the alpha subunit or beta subunit of S-100 protein. S-100b protein immunoreactivity was detected in Langerhans cells, interdigitating reticulum cells, and histiocytosis X cells, but not in ordinary macrophages and blood monocytes. In contrast, S-100ao protein immunoreactivity was detected in blood monocytes, macrophages of lymph node, alveolar macrophages of lung, and small numbers of Kupffer cells of liver. S-100ao immunoreactivity was also detected in epithelioid cells, Langhans giant cells, and foreign body giant cells. The present findings suggest that the presence of S-100ao protein in the cytoplasm is one of the characteristic features of cells in the human mononuclear phagocyte system. The detection of S-100b, but not S-100ao, immunoreactivity in Langerhans cells and interdigitating reticulum cells also suggests that they are independent of the monocyte-macrophage system. S-100ao protein may be a novel cytoplasmic marker for cells of the human monocyte-macrophage system.

Biomarkers↗

PubMed2003

Amniotic fluid levels of S100B protein in normal and trisomy-21 foetuses.

BACKGROUND: The human chromosome 21 has been shown to contain the gene for the beta subunit of the S100B protein. The present case-control study was aimed at investigating whether overproduction of S100B protein is detectable in the amniotic fluid of foetuses with trisomy-21. METHODS: Measurements of S100B in amniotic fluid samples from 14 pregnant women with trisomy-21 foetuses were compared with those obtained from 182 physiological pregnancies. S100B was measured in the samples using an immunoluminometric assay (LIA-mat Sangtec 100). RESULTS: Our results showed that S100B protein amniotic fluid levels were significantly higher in trisomy-21 foetuses (0.83+/-0.21 microg/l) than in controls (0.51+/-0.22 microg/l) (p<0.05). CONCLUSION: The present finding supports the notion that the expression of S100B is increased in trisomy-21 foetuses; it also constitutes a prerequisite basis for a possible involvement of the protein in pathogenic processes associated with trisomy-21, and/or for its potential employment as a diagnostic tool.

Adult↗

PubMed2001

Distribution of P2X receptors on astrocytes in juvenile rat hippocampus.

Recent evidence suggested that ATP acting via ionotropic (P2X) and metabotropic (P2Y) purinergic receptors might be involved in signaling between glial cells and within glial-neuronal networks. In contrast to their neuronal counterpart, the identity of P2X receptors in CNS glial cells is largely unknown. In the present study, antibodies recognizing the subunits P2X1-P2X7 were applied together with the astroglial marker S100beta and nuclear labeling with Hoechst 33342 to investigate semiquantitatively the distribution of the whole set of P2X receptors in astrocytes of the juvenile rat hippocampus. Expression of P2X1-P2X4, P2X6, and P2X7 subunits was observed in astrocytes of various hippocampal subregions, but the cells were completely devoid of P2X5 protein. S100beta-positive cells expressing subunits P2X3-P2X7 occurred evenly in the different subfields, while P2X1- and P2X2-positive astrocytes were distributed more heterogeneously. The staining pattern of P2X subunits also differed at the subcellular level. Antibodies against P2X2 and P2X4 labeled both astroglial cell bodies and processes. Immunoreactivity for P2X1 and P2X6 was mainly confined to somatic areas of S100beta-positive cells, whereas the subunit P2X3 was primarily localized along astroglial processes. Knowledge of the distribution of P2X receptors might provide a basis for a better understanding of their specific role in cell-cell signaling.

Adenosine Triphosphate↗

PubMed1998

S100B(betabeta) inhibits the protein kinase C-dependent phosphorylation of a peptide derived from p53 in a Ca2+-dependent manner.

S100B(betabeta) is a dimeric Ca2+-binding protein that is known to inhibit the protein kinase C (PKC)-dependent phosphorylation of several proteins. To further characterize this inhibition, we synthesized peptides based on the PKC phosphorylation domains of p53 (residues 367-388), neuromodulin (residues 37-53), and the regulatory domain of PKC (residues 19-31), and tested them as substrates for PKC. All three peptides were shown to be good substrates for the catalytic domain of PKC. As for full-length p53 (Baudier J, Delphin C, Grunwald D, Khochbin S, Lawrence JJ. 1992. Proc Natl Acad Sci USA 89:11627-11631), S100B(betabeta) binds the p53 peptide and inhibits its PKC-dependent phosphorylation (IC50 = 10 +/- 7 microM) in a Ca2+-dependent manner. Similarly, phosphorylation of the neuromodulin peptide and the PKC regulatory domain peptide were inhibited by S100B(betabeta) in the presence of Ca2+ (IC50 = 17 +/- 5 microM; IC50 = 1 +/- 0.5 microM, respectively). At a minimum, the C-terminal EF-hand Ca2+-binding domain (residues 61-72) of each S100beta subunit must be saturated to inhibit phosphorylation of the p53 peptide as determined by comparing the Ca2+ dependence of inhibition ([Ca]IC50 = 29.3 +/- 17.6 microM) to the dissociation of Ca2+ from the C-terminal EF-hand Ca2+-binding domain of S100B(betabeta).

Amino Acid Sequence↗

PubMed1996

Solution structure of rat apo-S100B(beta beta) as determined by NMR spectroscopy.

S100B(beta beta), a member of the S100 protein family, is a Ca(2+)-binding protein with noncovalent interactions at its dimer interface. Each apo-S100 beta subunit (91 residues) has four alpha-helices and a small antiparallel beta-sheet, consistent with two predicted helix-loop-helix Ca(2+)-binding domains known as EF-hands [Amburgey et al. (1995) J. Biomol. NMR 6, 171-179]. The three-dimensional solution structure of apo-S100B(beta beta) from rat has been determined using 2672 distance (14.7 per residue) and 88 dihedral angle restraints derived from multidimensional nuclear magnetic resonance spectroscopy. Apo-S100B (beta beta) is found to be globular and compact with an extensive hydrophobic core and a highly charged surface, consistent with its high solubility. At the symmetric dimer interface, 172 intermolecular nuclear Overhauser effect correlations (NOEs) define the antiparallel alignment of helix I with I' and of helix IV with IV'. The perpendicular association of these pairs of antiparallel helices forms an X-type four-helical bundle at the dimer interface. Whereas, the four helices within each apo-S100 beta subunit adopt a unicornate-type four-helix bundle, with helix I protruding from the parallel bundle of helices II, III, and IV. Accordingly, the orientation of helix III relative to helices I, II, and IV in each subunit differs significantly from that known for other Ca(2+)-binding proteins. Indeed, the interhelical angle (omega) observed in the C-terminal EF-hand of apo-S100 beta is -142 degrees, whereas omega ranges from 118 degrees to 145 degrees in the apo state and from 84 degrees to 128 degrees in the Ca(2+)-bound state for the EF-hands of calbindin D9k, calcyclin, and calmodulin. Thus, a significant conformational change in the C-terminal EF-hand would be required for it to adopt a structure typical of the Ca(2+)-bound state, which could readily explain the dramatic spectral effects observed upon the addition of Ca2+ to apo-S100B(beta beta).

Amino Acid Sequence↗