Document Detail


Structural requirements of the cytoplasmic domains of the human macrophage Fc gamma receptor IIa and B cell Fc gamma receptor IIb2 for the endocytosis of immune complexes.
MedLine Citation:
PMID:  1832386     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Two isotypes of the monocyte/macrophage as well as B cell Fc gamma receptor type II (FcRIIa and FcRIIb2, respectively) mainly differ in the length (76 vs. 44 amino acids) and amino acid sequence of their cytoplasmic domains. Only the eight amino acids just behind the putative transmembrane region are identical. Despite this marked difference, both FcRII mediate endocytosis of immune complexes. To determine the functional significance of the cytoplasmic domains, we expressed truncated FcRIIa and FcRIIb2 in FcR- BHK-21 cells. Mutants of both receptors containing only one amino acid (tail-minus) of the cytoplasmic domain failed to mediate immune complex uptake. The significance of the cytoplasmic domain of the receptors could be further demonstrated using a chimeric FcRIII-FcRIIa construct. Therefore we expressed an FcRIII lacking the hydrophobic carboxyl terminus (containing the putative phosphatidyl - inositol - glycan anchor site) fused inframe to the transmembrane and cytoplasmic domain of the FcRIIa in BHK-21 cells. In contrast to the wild type FcRIII, this chimeric receptor mediated immune complex uptake indistinguishable from that mediated by the FcRIIa. Receptor mutants with relatively short cytoplasmic domains (FcRIIb2: 13, and FcRIIa: 16 amino acids) revealed, that these short amino acid stretches are sufficient to allow reduced receptor-mediated endocytosis of bound ligand. Furthermore, using FcRIIa deletion mutants with a cytoplasmic domain consisting of 62, 46, and 28 amino acids, respectively, we found that the capability of these mutants to mediate immune complex uptake decreased gradually with the truncation of the cytoplasmic tails. Thus, only short amino acid sequences of the cytoplasmic domain are sufficient to enable an, albeit reduced, receptor-mediated endocytosis.
Authors:
W Engelhardt; H Gorczytza; A Butterweck; H Mönkemann; J Frey
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  European journal of immunology     Volume:  21     ISSN:  0014-2980     ISO Abbreviation:  Eur. J. Immunol.     Publication Date:  1991 Sep 
Date Detail:
Created Date:  1991-10-11     Completed Date:  1991-10-11     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  1273201     Medline TA:  Eur J Immunol     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  2227-38     Citation Subset:  IM    
Affiliation:
Universität Bielefeld, Fakultät für Chemie-Biochemie II, Bielefeld, FRG.
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MeSH Terms
Descriptor/Qualifier:
Animals
Antigen-Antibody Complex / metabolism*
Antigens, CD / immunology*
Antigens, Differentiation / immunology*
Base Sequence
Cell Line
Cricetinae
Endocytosis / immunology*
Flow Cytometry
Immunoglobulin G / metabolism
Macrophages / immunology*
Molecular Sequence Data
Mutagenesis, Site-Directed
Oligonucleotide Probes / genetics
Receptors, Fc / immunology*,  ultrastructure
Receptors, IgG
Transfection
Chemical
Reg. No./Substance:
0/Antigen-Antibody Complex; 0/Antigens, CD; 0/Antigens, Differentiation; 0/Immunoglobulin G; 0/Oligonucleotide Probes; 0/Receptors, Fc; 0/Receptors, IgG

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