Polymorphism of Complement Component I in Mongoloid Populations: A New Genetic Variant IF A2

Ding, Mei; Umetsu, Kazuo; Yuasa, Isao; Nakamura, Shigeki; Choi, Won Young; Suzuki, Tsuneo

doi:10.1159/000154002

Cited by 3 publications

(3 citation statements)

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“…Since IF*A3 is at present restricted to the Urubu-Kaapor, it can be provisionally labeled as a "private" polymorphism (Tanis et al, 1974(Tanis et al, , 1977. IF*A, which occurs with polymorphic frequencies in the various Mongoloid populations (Nakamura and Abe, 1985;Ding et al, in press), was not encountered in our present material.…”

Section: Discussioncontrasting

confidence: 52%

Isoelectric focusing studies in Brazilian Indians —uncovering variation of ORM, AHSG and IF—

et al. 1990

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SummaryAllele frequencies for the orosomucoid 1 (ORM1), orosomucoid 2 (ORM2), alpha-2-HS-glycoprotein (AHSG) and complement component I (IF) loci were studied in 393 individuals of three Brazilian Indian tribes. In the ORM1 locus only two alleles were observed among the Urubu-Kaapor, while five were found among the Pacafis Novos. The frequency of ORMI*I was similar in these two tribes (0.734 and 0.715, respectively) but departed more markedly among the Parakan~ (0.870). Variation for ORM2 locus was found among the Pacafis Novos only, with ORM2*3 being observed in just three individuals. A new variant (AHSG*PN) was found in the AHSG system. Frequency for AHSG*I was unexpectedly low in the three tribes, especially, among the Paca/ts Novos, where the prevalence (0.145) is the lowest considering other data reported thus far. For IF locus, variability was also restricted to only one trible (Urubu-Kaapor) and attributed to a new polymorphic allele, IF*A3.

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Section: Discussioncontrasting

confidence: 52%

Isoelectric focusing studies in Brazilian Indians —uncovering variation of ORM, AHSG and IF—

et al. 1990

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“…Two common autosomal codominant alleles, IF*A and IF*B and two rare alleles IF*A1 and IF*B1 have been reported [7][8][9]. Just like the seventh component (C7), IF shows a higher variation among Mongoloids than among Caucasoids [10][11][12]. The present investigation is a report of the IF polymorphism in a Chinese Han population in southwest China.…”

Section: Introductionmentioning

confidence: 62%

Genetic Polymorphism of Human Complement Factor I (C3b Inactivator) in the Chinese Han Population

Zhang

Stradmann‐Bellinghausen²,

Rittner³

et al. 1999

Exp Clin Immunogenet

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The human complement factor I (IF) polymorphism has been analysed by polyacrylamide gel isoelectric focusing electrophoresis of neuraminidase-treated EDTA plasma samples followed by immunoblotting and enzymatic detection. In a population study among 121 random individuals from Chengdu, PR China, three different common phenotypes were observed. The results show that IF is polymorphic in the Chinese population. The allele frequencies were as follows: FI*A = 0.153, FI*B = 0.847. The distribution of observed phenotypes was in accordance with the Hardy-Weinberg equilibrium. In comparison to other Asian population studies, the frequency of the IF*A allele was the highest in the Chinese population studied here.

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“…So far the two variant alleles appear to be restricted to the mongoloid population [74] as Finns, Germans, Senegalese, Turks and Indians were found to be monomorphic for the allele predominant in the Japanese [71]. In contrast homozygous Int Rev Immunol Downloaded from informahealthcare.com by McMaster University on 11/03/14…”

Section: Protein Polymorphism Detection Gene Frequencies a Codominmentioning

confidence: 99%

Genetics and Deficiencies of the Soluble Regulatory Proteins of the Complement System

Sim

Kölble

McAleer

et al. 1993

International Reviews of Immunology

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Int Rev Immunol Downloaded from informahealthcare.com by McMaster University on 11/03/14 For personal use only. 66 R. B. SIM et ul.The activation and regulation of the complement system are presented in more detail in several reviews [2-41. Complement activation via the classical pathway ( Fig. 1) is initiated by the binding of the Cl complex to complement activators, such as immune complexes. This results in activation of the serine proteases Clr and Cls, within Cl. Activated Cls then cleaves and activates C4 and C2: the number of molecules of C4 and C2 cleaved is regulated by theaction of C1-inhibitor on Cls. When C4 is activated, the major fragment, C4b, has an exposed, activated thiolester, which reacts rapidly with any nearby electron-donating (nucleophilic) species. C4b may react with an amine or hydroxyl group on the surface of the complement activator, and thus becomes covalently bound, by an ester or amide linkage, to the activator. Most of the C4b generated, however, simply reacts with water, and diffuses away from the site of complement activation. C2 binds to C4b, and if the C2 is appropriately oriented towards Cls, Cls cleaves C2, forming a complex consisting of C4b and C2a, the major fragment of C2. Since in physiological conditions Cls is bound to the complement activator, within the C1 complex, only C4b molecules which bind to the activator, very close to the C1 complex, will take part in formation of C4b2a. The C4b2a complex is a protease ("C3 convertase"), with its active site in C2a, which cleaves and activates C3. The activity of C4b2a is regulated by 3 mechanisms: firstly, the C4b2a complex is unstable, and dissociates irreversibly with a half-life of about 5 minutes. Secondly, C4bp binds to C4b in competition with C2, and can therefore inhibit formation of the C4b-C2 complex, and also accelerates the dissociation of C2a from C4b. The latter activity is named the "decay-acceleration'' activity of C4bp (Fig. 2): the membrane-bound regulatory proteins DAF and CR1 also possess this activity. Thirdly, C4b which is bound to C4bp is a substrate for factor I, which cleaves C4b to form two products, C4c (140kD) and C4d (45kD). This activity of C4bp is termed "factor I-cofactor" activity ( Fig. 2): CR1 and MCP also have this activity. C4c and C4d are not known to have any biological activity. Thus C4b, which mediates immune adherence and functions as part of the C3 and C5 convertase enzymes, is broken down to inactive products by the factor I + cofactor system. Once C3 is activated by C4b2a, the major fragment, C3b, behaves like C4b: via a thiolester, it may bind covalently to the surface of the complement activator, or it may react with water and diffuse away. One molecule of C3b binds directly to the C4b in C4b2a, forming C4b2a3b ("C5 convertase"): the C4b and C3b subunits of this complex bind C5, orienting it for cleavage by C2a [5-71. Cleavage of C5 to C5b initiates the assembly of the C5b, C6, C7, C8, C9 complex (C5b-9, also called MAC (membrane attack complex) or TCC (terminal complement complex...

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Polymorphism of Complement Component I in Mongoloid Populations: A New Genetic Variant IF A2

Cited by 3 publications

References 6 publications

Isoelectric focusing studies in Brazilian Indians —uncovering variation of ORM, AHSG and IF—

Isoelectric focusing studies in Brazilian Indians —uncovering variation of ORM, AHSG and IF—

Genetic Polymorphism of Human Complement Factor I (C3b Inactivator) in the Chinese Han Population

Genetics and Deficiencies of the Soluble Regulatory Proteins of the Complement System

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