20:
28:
159:
can inhibit the formation of the C3 convertase by competing with factor B for binding to C3b; accelerate the decay of the C3 convertase; and act as a cofactor for factor I-mediated cleavage of C3b. Complement factor H preferentially binds to vertebrate cells (because of affinity for sialic acid
112:
BbP or C4b2a3b from the classical pathway), the complement system follows the same path regardless of the means of activation (alternative, classical, or lectin). C5-convertase cleaves C5 into C5a and C5b. C5b binds sequentially to C6, C7, C8 and then to multiple molecules of C9 to form
125:
Since C3b is free and abundant in the plasma, it can bind to either a host cell or a pathogen surface. To prevent complement activation from proceeding on the host cell, there are several different kinds of regulatory proteins that disrupt the complement activation process:
93:. This convertase, the alternative pathway C3-convertase, although only produced in small amounts, can cleave multiple C3 proteins into C3a and C3b. The complex is believed to be unstable until it binds
166:(Complement factor H-Related protein 5) is able to bind to act as a cofactor for factor I, has decay accelerating activity and is able to bind preferentially to C3b at host surfaces.
339:"Human complement C3b inactivator: isolation, characterization, and demonstration of an absolute requirement for the serum protein beta1H for cleavage of C3b and C4b in solution"
149:
cleaves C3b into its inactive form, iC3b. Factor I requires a C3b-binding protein cofactor such as complement factor H, CR1, or membrane cofactor of proteolysis (MCP or
97:, a serum protein. The addition of properdin forms the complex C3bBbP, a stable compound which can bind an additional C3b to form alternative pathway C5-convertase.
388:"Human factor H-related protein 5 has cofactor activity, inhibits C3 convertase activity, binds heparin and C-reactive protein, and associates with lipoprotein"
533:
188:
187:. Alternative pathway activation also plays a significant role in complement-mediated renal disorders such as atypical hemolytic uremic syndrome,
231:"Interaction of beta1H globulin with cell-bound C3b: quantitative analysis of binding and influence of alternative pathway components on binding"
432:"Revisiting the role of factor H in age-related macular degeneration: Insights from complement-mediated renal disease and rare genetic variants"
974:
526:
502:
142:) compete with Factor B in binding with C3b on the cell surface and can even remove Bb from an already formed C3bBb complex
386:
McRae JL, Duthy TG, Griggs KM, Ormsby RJ, Cowan PJ, Cromer BA, McKinstry WJ, Parker MW, Murphy BF, Gordon DL (May 2005).
430:
Tzoumas, Nikolaos; Hallam, Dean; Harris, Claire L.; Lako, Majlinda; Kavanagh, David; Steel, David H.W. (November 2020).
1188:
519:
176:
160:
residues), allowing preferential protection of host (as opposed to bacterial) cells from complement-mediated damage.
865:
180:
967:
860:
803:
997:
204:
175:
Dysregulation of the complement system has been implicated in several diseases and pathologies, including
1389:
960:
689:
1243:
135:
511:
1323:
1193:
1158:
1153:
1048:
1043:
1038:
869:
627:
114:
1213:
1203:
1198:
1148:
1127:
1072:
1055:
891:
609:
545:
183:(AMD) is now believed to be caused, at least in part, by complement overactivation in retinal
1295:
1290:
1091:
838:
694:
672:
192:
1305:
1300:
855:
788:
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623:
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48:
8:
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1101:
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667:
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146:
71:
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255:
230:
447:
314:
279:
983:
783:
549:
498:
471:
459:
451:
409:
368:
319:
260:
145:
The formation of a C3 convertase can also be prevented when a plasma protease called
44:
431:
280:"Control of the amplification convertase of complement by the plasma protein beta1H"
58:
and kill pathogens. The pathway is triggered when the C3b protein directly binds a
1357:
1310:
1132:
903:
843:
815:
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778:
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443:
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40:
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1002:
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284:
Proceedings of the
National Academy of Sciences of the United States of America
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90:
59:
1368:
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1208:
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542:
62:. It can also be triggered by foreign materials and damaged tissues.
1111:
941:
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541:
94:
27:
19:
952:
1272:
1106:
931:
716:
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156:
75:
55:
936:
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54:
The alternative pathway is one of three complement pathways that
336:
908:
896:
641:
592:
100:
The C5-convertase of the alternative pathway consists of (C3b)
1314:
163:
495:
Immunobiology : the immune system in health and disease
1318:
1247:
1141:
337:
Pangburn MK, Schreiber RD, MĂĽller-Eberhard HJ (July 1977).
278:
Weiler JM, Daha MR, Austen KF, Fearon DT (September 1976).
150:
139:
131:
70:
This change in shape allows the binding of plasma protein
1137:
1065:
1060:
108:
Bb). After the creation of C5 convertase (either as (C3b)
429:
385:
277:
89:O)Bb. This complex is also known as a fluid-phase
23:The classical and alternative complement pathways.
31:Alternative pathway. (Some labels are in Polish.)
16:Type of cascade reaction of the complement system
1381:
228:
968:
527:
497:(5th ed.). New York: Garland Science.
491:"The complement system and innate immunity"
975:
961:
534:
520:
229:Conrad DH, Carlo JR, Ruddy S (June 1978).
403:
362:
313:
303:
254:
195:(Dense Deposit Disease or MPGN Type II).
179:in which kidney function is compromised.
51:, a natural defense against infections.
26:
18:
488:
1382:
982:
956:
515:
425:
423:
343:The Journal of Experimental Medicine
235:The Journal of Experimental Medicine
65:
78:to cleave Factor B into Ba and Bb.
13:
482:
177:atypical hemolytic uremic syndrome
170:
14:
1401:
448:10.1016/j.survophthal.2020.10.008
420:
104:BbP (sometimes referred to as C3b
181:Age related macular degeneration
861:Immunoglobulin class switching
379:
330:
271:
222:
130:Complement Receptor 1 (CR1 or
1:
215:
120:
489:Janeway, Charles A. (2005).
405:10.4049/jimmunol.174.10.6250
205:Classical complement pathway
7:
198:
10:
1408:
690:Polyclonal B cell response
47:and is a component of the
1344:
1281:
1244:Decay-accelerating factor
1228:
1181:
1120:
1023:
1016:
990:
924:
882:
824:
725:
655:
563:
556:
136:decay accelerating factor
81:Bb remains bound to C3(H
436:Survey of Ophthalmology
115:membrane attack complex
804:Tolerance in pregnancy
546:adaptive immune system
305:10.1073/pnas.73.9.3268
247:10.1084/jem.147.6.1792
32:
24:
839:Somatic hypermutation
673:Polyclonal antibodies
668:Monoclonal antibodies
392:Journal of Immunology
355:10.1084/jem.146.1.257
193:C3 glomerulonephritis
30:
22:
1283:Complement receptors
856:Junctional diversity
624:Antigen presentation
49:innate immune system
851:V(D)J recombination
834:Affinity maturation
586:Antigenic variation
296:1976PNAS...73.3268W
157:Complement factor H
147:complement factor I
37:alternative pathway
1112:Factor P/Properdin
1017:Activators/enzymes
33:
25:
1390:Complement system
1377:
1376:
1224:
1223:
984:Complement system
950:
949:
878:
877:
628:professional APCs
504:978-0-8153-4101-7
189:C3 glomerulopathy
66:Signaling cascade
45:complement system
1397:
1358:immune adherence
1021:
1020:
977:
970:
963:
954:
953:
844:Clonal selection
816:Immune privilege
811:Immunodeficiency
766:Cross-reactivity
756:Hypersensitivity
561:
560:
536:
529:
522:
513:
512:
508:
476:
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427:
418:
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383:
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366:
334:
328:
327:
317:
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275:
269:
268:
258:
241:(6): 1792–1805.
226:
41:cascade reaction
1407:
1406:
1400:
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1398:
1396:
1395:
1394:
1380:
1379:
1378:
1373:
1340:
1277:
1220:
1177:
1116:
1012:
986:
981:
951:
946:
920:
874:
820:
799:Clonal deletion
727:
721:
651:
552:
540:
505:
485:
483:Further reading
480:
479:
428:
421:
384:
380:
335:
331:
276:
272:
227:
223:
218:
201:
173:
171:Role in disease
123:
111:
107:
103:
88:
85:O) to form C3(H
84:
74:, which allows
68:
17:
12:
11:
5:
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828:
826:Immunogenetics
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821:
819:
818:
813:
808:
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806:
801:
796:
791:
786:
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771:Co-stimulation
768:
763:
758:
753:
748:
743:
738:
731:
729:
723:
722:
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719:
714:
712:Immune complex
708:
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685:
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632:Dendritic cell
620:
619:
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610:Conformational
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583:
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531:
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484:
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477:
442:(2): 378–401.
419:
398:(10): 6250–6.
378:
329:
290:(9): 3268–72.
270:
220:
219:
217:
214:
213:
212:
210:Lectin pathway
207:
200:
197:
172:
169:
168:
167:
161:
154:
143:
138:also known as
122:
119:
109:
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86:
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67:
64:
15:
9:
6:
4:
3:
2:
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1324:Anaphylatoxin
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1200:
1197:
1195:
1192:
1191:
1190:
1187:
1186:
1184:
1180:
1174:
1173:C5-convertase
1171:
1169:
1168:C3-convertase
1166:
1165:
1160:
1157:
1155:
1152:
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832:
831:
829:
827:
823:
817:
814:
812:
809:
805:
802:
800:
797:
795:
794:Clonal anergy
792:
790:
787:
785:
782:
781:
780:
776:
775:
772:
769:
767:
764:
762:
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718:
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698:
696:
693:
691:
688:
684:
683:Microantibody
681:
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569:
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415:
411:
406:
401:
397:
393:
389:
382:
374:
370:
365:
360:
356:
352:
349:(1): 257–70.
348:
344:
340:
333:
325:
321:
316:
311:
306:
301:
297:
293:
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274:
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152:
148:
144:
141:
137:
133:
129:
128:
127:
118:
116:
98:
96:
92:
91:C3-convertase
79:
77:
73:
63:
61:
57:
52:
50:
46:
42:
39:is a type of
38:
29:
21:
1369:Opsonization
1364:inflammation
1352:Cytotoxicity
1269:
1259:
1239:C1-inhibitor
1235:
1098:
1079:
1030:
1007:
761:Inflammation
746:Alloimmunity
741:Autoimmunity
726:Immunity vs.
678:Autoantibody
576:Superantigen
494:
439:
435:
395:
391:
381:
346:
342:
332:
287:
283:
273:
238:
234:
224:
174:
124:
99:
80:
69:
53:
36:
34:
884:Lymphocytes
543:Lymphocytic
134:) and DAF (
1229:Inhibitors
925:Substances
789:Peripheral
777:Inaction:
656:Antibodies
637:Macrophage
550:complement
216:References
121:Regulation
1362:Inducing
942:Cytolysin
932:Cytokines
779:Tolerance
728:tolerance
647:Immunogen
472:226274874
456:0039-6257
95:properdin
1384:Category
1354:(by MAC)
1345:Function
1273:Factor H
1253:Factor I
1107:Factor D
1102:Factor B
991:Pathways
892:Cellular
736:Immunity
734:Action:
717:Paratope
705:Idiotype
695:Allotype
663:Antibody
617:Mimotope
581:Allergen
564:Antigens
557:Lymphoid
464:33157112
414:15879123
199:See also
76:Factor D
72:Factor B
56:opsonize
937:Opsonin
916:NK cell
904:Humoral
784:Central
751:Allergy
700:Isotype
600:Epitope
571:Antigen
364:2180748
324:1067618
292:Bibcode
256:2184316
185:tissues
60:microbe
43:of the
1121:Middle
909:B cell
897:T cell
642:B cell
605:Linear
593:Hapten
501:
470:
462:
454:
412:
373:301546
371:
361:
322:
315:431003
312:
265:567241
263:
253:
191:, and
1315:CD11c
1311:CD11b
1087:MASP2
1083:MASP1
1024:Early
468:S2CID
164:CFHR5
1319:CD18
1263:C4BP
1248:CD59
1236:CLA:
1182:Late
1142:iC3b
548:and
499:ISBN
460:PMID
452:ISSN
410:PMID
369:PMID
320:PMID
261:PMID
151:CD46
140:CD55
132:CD35
35:The
1334:C5a
1329:C3a
1306:CR4
1301:CR3
1296:CR2
1291:CR1
1260:CL:
1194:C5b
1189:MAC
1159:C5b
1154:C5a
1138:C3b
1133:C3a
1092:MBL
1066:C4b
1061:C4a
1049:C1s
1044:C1r
1039:C1q
870:HLA
866:MHC
444:doi
400:doi
396:174
359:PMC
351:doi
347:146
310:PMC
300:doi
251:PMC
243:doi
239:147
1386::
1270:A:
1214:C9
1209:C8
1204:C7
1199:C6
1149:C5
1128:C3
1099:A:
1080:L:
1073:C2
1056:C4
1034:C1
1031:C:
630::
493:.
466:.
458:.
450:.
440:66
438:.
434:.
422:^
408:.
394:.
390:.
367:.
357:.
345:.
341:.
318:.
308:.
298:.
288:73
286:.
282:.
259:.
249:.
237:.
233:.
117:.
1317:/
1313:/
1246:/
1140:/
1085:/
1008:A
1003:L
998:C
976:e
969:t
962:v
868:/
626:/
535:e
528:t
521:v
507:.
474:.
446::
416:.
402::
375:.
353::
326:.
302::
294::
267:.
245::
153:)
110:2
106:2
102:2
87:2
83:2
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
