FCGR2B
Fc-fragment IgG receptora IIb jest protein koji je kod ljudi kodiran genom FCGR2B sa hromosoma 1. Za Fc-regiju imunoglobulina gama (IgG) niski su afiniteti inhibitornih receptora. FCGR2B učestvuje u fagocitozi imunskih kompleksa i u regulaciji proizvodnje antitijela putem B-limfocita.[5]
Aminokiselinska sekvenca
urediDužina polipeptidnog lanca je 310 aminokiselina, a molekulska težina 34.044 Da.[6]
10 | 20 | 30 | 40 | 50 | ||||
---|---|---|---|---|---|---|---|---|
MGILSFLPVL | ATESDWADCK | SPQPWGHMLL | WTAVLFLAPV | AGTPAAPPKA | ||||
VLKLEPQWIN | VLQEDSVTLT | CRGTHSPESD | SIQWFHNGNL | IPTHTQPSYR | ||||
FKANNNDSGE | YTCQTGQTSL | SDPVHLTVLS | EWLVLQTPHL | EFQEGETIVL | ||||
RCHSWKDKPL | VKVTFFQNGK | SKKFSRSDPN | FSIPQANHSH | SGDYHCTGNI | ||||
GYTLYSSKPV | TITVQAPSSS | PMGIIVAVVT | GIAVAAIVAA | VVALIYCRKK | ||||
RISALPGYPE | CREMGETLPE | KPANPTNPDE | ADKVGAENTI | TYSLLMHPDA | ||||
LEEPDDQNRI |
Struktura
urediPostoje dva glavna oblika FCGR2B (FCGR2B1 i FCGR2B2) i oni su stvoreni mehanizmom prerade iRNK, što rezultira uključivanjem (FCGR2B1) ili isključenjem (FCGR2B2) sekvence egzona C1. Prisustvo sekvence egzona C1 (u FCGR2B1) dovodi do vezivanja za membranu B-ćelija, dok njeno odsustvo (u FCGR2B2) omogućava brzu internalizaciju receptora u mijeloidnim ćelijama. Oba oblika sadrže Inhibitorni motiv zasnovan na imunoreceptoru tirozina (ITIM) u svojim citoplazmatskim regijama. Vanćelijski domeni su 95% identični domenima FCGR2A i skoro potpuno identični FCGR2C (ostali članovi porodice CD32).[7]
Ekaspresija
urediFCGR2B1 je visoko eksprimiran u B-ćelijama, a njegova iRNK je također identificirana na nižim nivoima na monocitiima. FCGR2B2 je visoko izražen na bazofilima i na niskim nivoima na monocitima. Regulacija ekspresije citokina je pozitivna u slučaju IL-10 i IL-6, a negativna u slučaju TNF-α , C5a i IFN-γ.[7]
Funkcija
urediReceptor inhibira funkcije aktiviranja FcγR, kao što je fagocitoza i proupalno oslobađanje citokina, uglavnom grupiranjem FCGR2B s različitim aktivirajućim FCGR receptorima ili sa BCR pomoću imunskih kompleksa.[7][8]
Fosforilizirani ITIM FcγRIIB regrutuje inozitol-fosfataze SHIP1 i SHIP2, koje inhibiraju aktivaciju Ras, smanjujući aktivnost MAPK i smanjujući funkciju PLCγ i dovode do smanjene aktivacije PKC. Inhibicija puta MAP-kinaze, zajedno sa antiapoptotskom kinazom Akt, može negativno uticati na proliferaciju i preživljavanje ćelija.[7]
FCGR2B regulira aktivaciju B-ćelija povećanjem praga aktivacije BCR i potiskivanjem prezentacije antigena posredovane B– i T-ćelijama preko ITIM-ovisnog inhibitornog mehanizma.[8] Ligacija FCGR2B na B-ćelijama smanjuje regulaciju antitijela, sprečavajući membransku organizaciju BCR i CD19 i promovira apoptozu. Koligacija FCGR2B na dendritskim ćelijama inhibira sazrijevanje i blokira aktivaciju ćelija.[7] Negativna regulatorna uloga FCGRIIB molekula nije ograničena na BCR-indukovanu aktivaciju B-ćelija, već je također funkcionalna na drugim putevima aktivacije B-ćelija posredovane putem CD40 i IL-4.[9]
Ekspresija FCGR2B na folikulskim dendritskim ćelijama (FDCs) je važna za hvatanje imunskih kompleksa koji sadrže antigen koji su neophodni za odgovor germinalnog centra.[8]
FCGR2B je prisutan na neleukocitnim ćelijama, uključujući glatke mišiće disajnih puteva i sinusoidne endotelne ćelije jetre, gdje su mali imunski kompleksi internalizovani i inhibiraju proupalnu signalizaciju.[7]
FCGR2B je jedan od gena za koje se smatra da utiču na osjetljivost na nekoliko autoimunskih bolesti kod ljudi. Njegova smanjena funkcija povezana je sa sistemskim eritemskim lupusom, reumatoidnim artritisom, Goodpastureovom bolešću, multiplom sklerozom i drugim.[8]
FCGR2B može biti meta za terapiju monoklonskim antitijelima za autoimunske i maligne bolesti.[8][10][11]
Također pogledajte
urediReference
uredi- ^ a b c GRCh38: Ensembl release 89: ENSG00000072694 - Ensembl, maj 2017
- ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000026656 - Ensembl, maj 2017
- ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
- ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
- ^ "FCGR2B Fc fragment of IgG receptor IIb [Homo sapiens (human)] - Gene - NCBI". www.ncbi.nlm.nih.gov. Pristupljeno 14. 6. 2019.
- ^ "UniProt, P31994" (jezik: en.). Pristupljeno 10. 12. 2021.CS1 održavanje: nepoznati jezik (link)
- ^ a b c d e f Anania JC, Chenoweth AM, Wines BD, Hogarth PM (19. 3. 2019). "The Human FcγRII (CD32) Family of Leukocyte FcR in Health and Disease". Frontiers in Immunology. 10: 464. doi:10.3389/fimmu.2019.00464. PMC 6433993. PMID 30941127.
- ^ a b c d e Smith, Kenneth G. C.; Clatworthy, Menna R. (6. 8. 2010). "Erratum: FcγRIIB in autoimmunity and infection: evolutionary and therapeutic implications". Nature Reviews Immunology. 10 (9): 674. doi:10.1038/nri2821. ISSN 1474-1733.
- ^ Horejs-Hoeck J, Hren A, Mudde GC, Woisetschläger M (juli 2005). "Inhibition of immunoglobulin E synthesis through Fc gammaRII (CD32) by a mechanism independent of B-cell receptor co-cross-linking". Immunology. 115 (3): 407–15. doi:10.1111/j.1365-2567.2005.02162.x. PMC 1782155. PMID 15946258.
- ^ Rankin CT, Veri MC, Gorlatov S, Tuaillon N, Burke S, Huang L, et al. (oktobar 2006). "CD32B, the human inhibitory Fc-gamma receptor IIB, as a target for monoclonal antibody therapy of B-cell lymphoma". Blood. 108 (7): 2384–91. doi:10.1182/blood-2006-05-020602. PMID 16757681.
- ^ Zhou P, Comenzo RL, Olshen AB, Bonvini E, Koenig S, Maslak PG, et al. (april 2008). "CD32B is highly expressed on clonal plasma cells from patients with systemic light-chain amyloidosis and provides a target for monoclonal antibody-based therapy". Blood. 111 (7): 3403–6. doi:10.1182/blood-2007-11-125526. PMC 2275009. PMID 18216299.
Dopunska literatura
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- Bewarder N, Weinrich V, Budde P, Hartmann D, Flaswinkel H, Reth M, Frey J (septembar 1996). "In vivo and in vitro specificity of protein tyrosine kinases for immunoglobulin G receptor (FcgammaRII) phosphorylation". Molecular and Cellular Biology. 16 (9): 4735–43. doi:10.1128/MCB.16.9.4735. PMC 231474. PMID 8756631.
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- Sondermann P, Huber R, Jacob U (mart 1999). "Crystal structure of the soluble form of the human fcgamma-receptor IIb: a new member of the immunoglobulin superfamily at 1.7 A resolution". The EMBO Journal. 18 (5): 1095–103. doi:10.1093/emboj/18.5.1095. PMC 1171201. PMID 10064577.
- Muraille E, Bruhns P, Pesesse X, Daëron M, Erneux C (april 2000). "The SH2 domain containing inositol 5-phosphatase SHIP2 associates to the immunoreceptor tyrosine-based inhibition motif of Fc gammaRIIB in B cells under negative signaling". Immunology Letters. 72 (1): 7–15. doi:10.1016/S0165-2478(00)00162-0. PMID 10789675.
- Pricop L, Redecha P, Teillaud JL, Frey J, Fridman WH, Sautès-Fridman C, Salmon JE (januar 2001). "Differential modulation of stimulatory and inhibitory Fc gamma receptors on human monocytes by Th1 and Th2 cytokines". Journal of Immunology. 166 (1): 531–7. doi:10.4049/jimmunol.166.1.531. PMID 11123333.
- Lyden TW, Robinson JM, Tridandapani S, Teillaud JL, Garber SA, Osborne JM, et al. (mart 2001). "The Fc receptor for IgG expressed in the villus endothelium of human placenta is Fc gamma RIIb2". Journal of Immunology. 166 (6): 3882–9. doi:10.4049/jimmunol.166.6.3882. PMID 11238632.
- Bharadwaj D, Mold C, Markham E, Du Clos TW (juni 2001). "Serum amyloid P component binds to Fc gamma receptors and opsonizes particles for phagocytosis". Journal of Immunology. 166 (11): 6735–41. doi:10.4049/jimmunol.166.11.6735. PMID 11359830.
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Vanjski linkovi
uredi- FCGR2B protein, human na US National Library of Medicine Medical Subject Headings (MeSH)
Ovaj članak uključuje tekst iz Nacionalne medicinske biblioteke Sjedinjenih Država, koji je u javnom vlasništvu.