Human serum amyloid P-component (SAP) selectively binds to immobilized or bound forms of C-reactive protein (CRP)

Swanson, Steven J.; Christner, Robert B.; Mortensen, Richard F.

doi:10.1016/0167-4838(92)90093-s

Cited by 16 publications

(8 citation statements)

References 40 publications

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“…Although the sensitivity of many AP aggregation assays may legitimately constrain such ex-AP Binding Proteins and AP Aggregation 59 molar ratios of 5: 1 and 20: 1, respectively. Solutions containing SAP also contained 2 mM Ca2+ , a condition that has been shown previously to be a prerequisite for SAP binding to itself, amyloid fibrils, heparin, and C-reactive protein (Pepys et al, 1979;Swanson et al, 1992;. Parallel studies with 2 mM Ca2+ alone showed no discernible effect on AP aggregation even at 24 hr, consistent with previous results (Mantyh et al, 1993).…”

Section: Introductionsupporting

confidence: 88%

Relative efficacies of amyloid ? peptide (A?) binding proteins in A? aggregation

Webster

Rogers

1996

J. Neurosci. Res.

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The aggregation of amyloid β peptide (Aβ) into its fibrillar, cross β‐pleated configuration is generally viewed as a critical event in the pathophysiology of Alzheimer's disease (AD). A diverse group of molecules, the Aβ binding proteins, has been evaluated for their effects on this process. However, most of these studies have used micromolar or greater reagent concentrations, and their different methods have not permitted quantitative comparisons of the efficacy of different Aβ binding proteins in augmenting or inhibiting aggregation. In the present work we have undertaken a coherent analysis using fluorimetry of thioflavin T‐stained experimental solutions. The complement protein C1q, serum amyloid P, and transthyretin significantly enhanced the formation of precipitable, cross β‐pleated aggregates in solutions of 800 nM Aβ1–42. Under these same experimental conditions, α1‐antichymotrypsin had no significant effect on the aggregation process, and both the E3 and E4 isoforms of apolipoprotein E were significant inhibitors. There was a non‐significant trend toward the E3 isoform exhibiting greater inhibition than the E4 isoform. Of the aggregation‐facilitating molecules, C1q was substantially and significantly the most potent. © 1996 Wiley‐Liss, Inc.

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Section: Introductionsupporting

confidence: 88%

Relative efficacies of amyloid ? peptide (A?) binding proteins in A? aggregation

Webster

Rogers

1996

J. Neurosci. Res.

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“…Despite in vitro results from systems involving separated, purified and/or denatured preparations of chromatin constituents [5][6][7]23], or using modified pentraxins [37], no binding of CRP to chromatin in situ was observed. Binding of SAP and CRP took place independently, to separate structures, and there was no evidence of any interaction between them, in contrast to results reported with CRP immobilized by solidphase capture via antibodies or ligands on plastic surfaces [38]. Binding to nuclei did not require the presence of any other serum factors.…”

Section: Discussioncontrasting

confidence: 51%

Binding of pentraxins to different nuclear structures: C-reactive protein binds to small nuclear ribonucleoprotein particles, serum amyloid P component binds to chromatin and nucleoli

Pepys¹,

Booth²,

Tennent³

et al. 1994

Clinical and Experimental Immunology

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SUMMARYBinding of the human pentraxin plasma proteins, C-reactive protein (CRP) and serum amyloid P component (SAP), to the nuclei of human cells was studied using whole acute phase serum as the source of the proteins and confocal immunofluorescence microscopy. CRP and SAP clearly bound to distinct, different structures. Double staining with MoAbs to the Sm D and Sm B/B' components of small nuclear ribonucleoproteins confirmed that CRP bound exclusively to these particles. As expected, SAP bound to chromatin and, in addition, binding to the nucleolus was observed for the first time. These interactions demonstrated under relatively physiological conditions, with native pentraxins unseparated from serum and with nuclear constituents in situ, are likely to be of functional importance in vivo.Keywords pentraxin nucleus chromatin C-reactive protein serum amyloid P component INTRODUCTIONInteractions between the pentraxins, C-reactive protein (CRP) and serum amyloid P component (SAP) in man, and constituents of cell nuclei are important because they may represent biologically significant roles of this conserved plasma protein family [1,2]. Although it is clear that both CRP [3] and SAP [4] bind to nuclei, there are conflicting reports about their respective specific ligands. This controversy arises in part because of differences in the methods used to demonstrate binding. In particular the use, as test ligands, of isolated purified nuclear constituents immobilized under conditions [5][6][7] in which denaturation is unavoidable [8], and the use of unphysiological buffers [9], may reveal interactions which are unlikely to occur in vivo. We have therefore investigated the binding to nuclei of native CRP and SAP from whole acute-phase serum, and used double label confocal immunofluorescence microscopy [10] for the highest degree of morphological resolution.

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“…SAP has a tendency to calcium-dependent self aggregation [20] and it binds calcium-dependent ly to several serum proteins although some of these interactions may not be physiologically relevant [14,[20][21][22][23][24]. The interaction between SAP and C4b-binding protein has been investigated with divergent results but it now seems established that complexes are formed with a molecular ratio of 1:1 [14,21].…”

Section: Discussionmentioning

confidence: 99%

Native Human Serum Amyloid P Component is a Single Pentamer

Sørensen¹,

Andersen

Svehag³

1995

Scand J Immunol

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Serum amyloid P component (SAP) and C-reactive protein (CRP) are members of the pentraxin protein family. SAP is the precursor protein to amyloid P component present in all forms of amyloidosis. The prevailing notion is that SAP in circulation has the form of a double pentameric molecule (decamer) whereas CRP is a single pentameric molecule. We have investigated by gel permeation chromatography the M(r) of SAP in freshly collected human serum and of SAP purified by carbohydrate affinity chromatography and anion exchange chromatography. SAP was monitored by quantitative immunoelectrophoresis and ELISA, and SAP peak fractions were analysed by use of SDS-PAGE, Western blotting, and electron microscopy. The results indicate that native SAP circulates as a single pentamer, a part of which forms complexes with C4b-binding protein. The properties of SAP changed during purification as indicated by rocket immunoelectrophoresis and electron microscopy. Thus, electron micrographs of purified SAP showed a predominance of decamers. However, the decamer form of SAP reversed to single pentamers when purified SAP was incorporated into SAP-depleted serum.

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Human serum amyloid P-component (SAP) selectively binds to immobilized or bound forms of C-reactive protein (CRP)

Cited by 16 publications

References 40 publications

Relative efficacies of amyloid ? peptide (A?) binding proteins in A? aggregation

Relative efficacies of amyloid ? peptide (A?) binding proteins in A? aggregation

Binding of pentraxins to different nuclear structures: C-reactive protein binds to small nuclear ribonucleoprotein particles, serum amyloid P component binds to chromatin and nucleoli

Native Human Serum Amyloid P Component is a Single Pentamer

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