Complement C4-B (Basic complement C4) (C3 and PZP-like alpha-2-macroglobulin domain-containing protein 3) [Cleaved into: Complement C4 beta chain; Complement C4-B alpha chain; C4a anaphylatoxin; C4b-B; C4d-B; Complement C4 gamma chain]
1_MRLLW 6_ GLIWA 11_ SSFFT 16_ LSLQK 21_ PRLLL 26_ FSPSV 31_ VHLGV 36_ PLSVG 41_ VQLQD 46_ VPRGQ 51_ VVKGS 56_ VFLRN 61_ PSRNN 66_ VPCSP 71_ KVDFT 76_ LSSER 81_ DFALL 86_ SLQVP 91_ LKDAK 96_ SCGLH 101_ QLLRG 106_ PEVQL 111_ VAHSP 116_ WLKDS 121_ LSRTT 126_ NIQGI 131_ NLLFS 136_ SRRGH 141_ LFLQT 146_ DQPIY 151_ NPGQR 156_ VRYRV 161_ FALDQ 166_ KMRPS 171_ TDTIT 176_ VMVEN 181_ SHGLR 186_ VRKKE 191_ VYMPS 196_ SIFQD 201_ DFVIP 206_ DISEP 211_ GTWKI 216_ SARFS 221_ DGLES 226_ NSSTQ 231_ FEVKK 236_ YVLPN 241_ FEVKI 246_ TPGKP 251_ YILTV 256_ PGHLD 261_ EMQLD 266_ IQARY 271_ IYGKP 276_ VQGVA 281_ YVRFG 286_ LLDED 291_ GKKTF 296_ FRGLE 301_ SQTKL 306_ VNGQS 311_ HISLS 316_ KAEFQ 321_ DALEK 326_ LNMGI 331_ TDLQG 336_ LRLYV 341_ AAAII 346_ ESPGG 351_ EMEEA 356_ ELTSW 361_ YFVSS 366_ PFSLD 371_ LSKTK 376_ RHLVP 381_ GAPFL 386_ LQALV 391_ REMSG 396_ SPASG 401_ IPVKV 406_ SATVS 411_ SPGSV 416_ PEVQD 421_ IQQNT 426_ DGSGQ 431_ VSIPI 436_ IIPQT 441_ ISELQ 446_ LSVSA 451_ GSPHP 456_ AIARL 461_ TVAAP 466_ PSGGP 471_ GFLSI 476_ ERPDS 481_ RPPRV 486_ GDTLN 491_ LNLRA 496_ VGSGA 501_ TFSHY 506_ YYMIL 511_ SRGQI 516_ VFMNR 521_ EPKRT 526_ LTSVS 531_ VFVDH 536_ HLAPS 541_ FYFVA 546_ FYYHG 551_ DHPVA 556_ NSLRV 561_ DVQAG 566_ ACEGK 571_ LELSV 576_ DGAKQ 581_ YRNGE 586_ SVKLH 591_ LETDS 596_ LALVA 601_ LGALD 606_ TALYA 611_ AGSKS 616_ HKPLN 621_ MGKVF 626_ EAMNS 631_ YDLGC 636_ GPGGG 641_ DSALQ 646_ VFQAA 651_ GLAFS 656_ DGDQW 661_ TLSRK 666_ RLSCP 671_ KEKTT 676_ RKKRN 681_ VNFQK 686_ AINEK 691_ LGQYA 696_ SPTAK 701_ RCCQD 706_ GVTRL 711_ PMMRS 716_ CEQRA 721_ ARVQQ 726_ PDCRE 731_ PFLSC 736_ CQFAE 741_ SLRKK 746_ SRDKG 751_ QAGLQ 756_ RALEI 761_ LQEED 766_ LIDED 771_ DIPVR 776_ SFFPE 781_ NWLWR 786_ VETVD 791_ RFQIL 796_ TLWLP 801_ DSLTT 806_ WEIHG 811_ LSLSK 816_ TKGLC 821_ VATPV 826_ QLRVF 831_ REFHL 836_ HLRLP 841_ MSVRR 846_ FEQLE 851_ LRPVL 856_ YNYLD 861_ KNLTV 866_ SVHVS 871_ PVEGL 876_ CLAGG 881_ GGLAQ 886_ QVLVP 891_ AGSAR 896_ PVAFS 901_ VVPTA 906_ ATAVS 911_ LKVVA 916_ RGSFE 921_ FPVGD 926_ AVSKV 931_ LQIEK 936_ EGAIH 941_ REELV 946_ YELNP 951_ LDHRG 956_ RTLEI 961_ PGNSD 966_ PNMIP 971_ DGDFN 976_ SYVRV 981_ TASDP 986_ LDTLG 991_ SEGAL 996_ SPGGV 1001_ ASLLR 1006_ LPRGC 1011_ GEQTM 1016_ IYLAP 1021_ TLAAS 1026_ RYLDK 1031_ TEQWS 1036_ TLPPE 1041_ TKDHA 1046_ VDLIQ 1051_ KGYMR 1056_ IQQFR 1061_ KADGS 1066_ YAAWL 1071_ SRGSS 1076_ TWLTA 1081_ FVLKV 1086_ LSLAQ 1091_ EQVGG 1096_ SPEKL 1101_ QETSN 1106_ WLLSQ 1111_ QQADG 1116_ SFQDL 1121_ SPVIH 1126_ RSMQG 1131_ GLVGN 1136_ DETVA 1141_ LTAFV 1146_ TIALH 1151_ HGLAV 1156_ FQDEG 1161_ AEPLK 1166_ QRVEA 1171_ SISKA 1176_ SSFLG 1181_ EKASA 1186_ GLLGA 1191_ HAAAI 1196_ TAYAL 1201_ TLTKA 1206_ PADLR 1211_ GVAHN 1216_ NLMAM 1221_ AQETG 1226_ DNLYW 1231_ GSVTG 1236_ SQSNA 1241_ VSPTP 1246_ APRNP 1251_ SDPMP 1256_ QAPAL 1261_ WIETT 1266_ AYALL 1271_ HLLLH 1276_ EGKAE 1281_ MADQA 1286_ AAWLT 1291_ RQGSF 1296_ QGGFR 1301_ STQDT 1306_ VIALD 1311_ ALSAY 1316_ WIASH 1321_ TTEER 1326_ GLNVT 1331_ LSSTG 1336_ RNGFK 1341_ SHALQ 1346_ LNNRQ 1351_ IRGLE 1356_ EELQF 1361_ SLGSK 1366_ INVKV 1371_ GGNSK 1376_ GTLKV 1381_ LRTYN 1386_ VLDMK 1391_ NTTCQ 1396_ DLQIE 1401_ VTVKG 1406_ HVEYT 1411_ MEANE 1416_ DYEDY 1421_ EYDEL 1426_ PAKDD 1431_ PDAPL 1436_ QPVTP 1441_ LQLFE 1446_ GRRNR 1451_ RRREA 1456_ PKVVE 1461_ EQESR 1466_ VHYTV 1471_ CIWRN 1476_ GKVGL 1481_ SGMAI 1486_ ADVTL 1491_ LSGFH 1496_ ALRAD 1501_ LEKLT 1506_ SLSDR 1511_ YVSHF 1516_ ETEGP 1521_ HVLLY 1526_ FDSVP 1531_ TSREC 1536_ VGFEA 1541_ VQEVP 1546_ VGLVQ 1551_ PASAT 1556_ LYDYY 1561_ NPERR 1566_ CSVFY 1571_ GAPSK 1576_ SRLLA 1581_ TLCSA 1586_ EVCQC 1591_ AEGKC 1596_ PRQRR 1601_ ALERG 1606_ LQDED 1611_ GYRMK 1616_ FACYY 1621_ PRVEY 1626_ GFQVK 1631_ VLRED 1636_ SRAAF 1641_ RLFET 1646_ KITQV 1651_ LHFTK 1656_ DVKAA 1661_ ANQMR 1666_ NFLVR 1671_ ASCRL 1676_ RLEPG 1681_ KEYLI 1686_ MGLDG 1691_ ATYDL 1696_ EGHPQ 1701_ YLLDS 1706_ NSWIE 1711_ EMPSE 1716_ RLCRS 1721_ TRQRA 1726_ ACAQL 1731_ NDFLQ 1736_EYGTQ
1: Precursor of non-enzymatic components of the classical, lectin and GZMK complement pathways, which consist in a cascade of proteins that leads to phagocytosis and breakdown of pathogens and signaling that strengthens the adaptive immune system
2: Non-enzymatic component of C3 and C5 convertases (By similarity). Generated following cleavage by complement proteases (C1S, MASP2 or GZMK, depending on the complement pathway), it covalently attaches to the surface of pathogens, where it acts as an opsonin that marks the surface of antigens for removal (By similarity). It then recruits the serine protease complement C2b to form the C3 and C5 convertases, which cleave and activate C3 and C5, respectively, the next components of the complement pathways (PubMed:8538770). Complement C4b-B isotype catalyzes the transacylation of the thioester carbonyl group to form ester bonds with carbohydrate antigens, while C4b-A isotype is responsible for effective binding to form amide bonds with immune aggregates or protein antigens (PubMed:8538770)
3: Putative humoral mediator released following cleavage by complement proteases (C1S, MASP2 or GZMK, depending on the complement pathway). While it is strongly similar to anaphylatoxins, its role is unclear. Was reported to act as a mediator of local inflammatory process; however these effects were probably due to contamination with C3a and/C5a anaphylatoxins in biological assays