Human lymphocyte Fc receptor for IgE: Sequence homology of its cloned cDNA with animal lectins

Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 03/1987; 84(3):819-23. DOI: 10.1073/pnas.84.3.819
Source: PubMed


We have purified the human lymphocyte Fc receptor specific for IgE (Fc epsilon receptor) and its soluble form by using the anti-Fc epsilon receptor monoclonal antibody H107. Using an oligonucleotide probe corresponding to the partial amino acid sequence of the soluble Fc epsilon receptor related to IgE binding factor, we cloned, sequenced, and expressed a cDNA for the receptor. The Fc epsilon receptor has 321 amino acid residues with no NH2-terminal signal sequence. The receptor was separated into two domains by a putative 24-amino acid residue transmembrane region located near the NH2-terminal end. The Fc epsilon receptor showed a marked homology with animal lectins including human and rat asialoglycoprotein receptors, chicken hepatic lectin, and rat mannose binding proteins.

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Available from: Yutaka Tagaya, Dec 13, 2013
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    • "The majority of " inside-out " membrane proteins are cell surface-receptor or ligand proteins. These include CD40L (Hollenbaugh et al. 1992), CD26 (Hegen et al. 1990; Tanaka et al. 1992), CD23 (Ikuta et al. 1987; Ludin et al. 1987), NKR-P1 (Yokoyama and Seaman 1993), and FasL (Suda et al. 1993). DMC1 has the " Pro-Pro-X-Pro " motif near the transmembrane domain. "
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    ABSTRACT: Frequent allelic losses within chromosomal band 17q25.1 in a variety of human cancers have suggested the presence of one or more tumor suppressor genes in this region. Furthermore, a genetic locus responsible for familial focal nonepidermolytic palmoplantar keratoderma, a condition associated with cancer of the esophagus, lies in the same region. This esophageal-cancer susceptibility locus, TOC (tylosis with oesophageal cancer), might be a target of deletions at 17q25.1 in multiple types of malignancy. Using the reverse transcriptase-polymerase chain reaction (RT-PCR) to examine cancer cell lines for alterations in the expression of transcripts from this portion of 17q, we identified a novel gene that we designated DMC1 (downregulated in multiple cancer-1). The full-length cDNA is 3293bp long. Its putative product is an integral membrane protein of 788 amino acids, belonging to the class of so-called 'inside-out" membrane proteins; it lacks a signal sequence but contains an N-terminal cytoplasmic domain, a single transmembrane peptide, and a C-terminal extracellular domain. We documented loss of expression of DMC1 in 2 of 10 breast-cancer cell lines, in 7 of 10 cervical-cancer lines, in 7 of 13 hepatocellular-cancer lines, in 3 of 7 lung-cancer lines, in 3 of 6 thyroid-cancer lines, in 2 of 6 gastric-cancer lines, and in 2 of 4 renal cell-cancer lines. Our results suggest that loss of expression of the DMC1 gene at 17q25.1 may play an important role in the development of cancers in a broad range of human tissues.
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    ABSTRACT: B cell-derived IgE-BFs (sCD23) are cleavage fragments of surface Fc epsilon R II. Their production is increased by IL4 and suppressed by IFN-gamma and IFN-alpha. IgE-BFs are likely to play a role in the regulation of human IgE synthesis as shown by the following two observations: i. MabER specifically blocks both the spontaneous IgE by synthesis by atopic B cells and the IL4-induced IgE synthesis by normal lymphocytes, ii. purified IgE-BFs enhance the IL4-induced and the spontaneous IgE synthesis. Soluble fragments of Fc epsilon R II also display BCGF-like activity although the exact structure of these fragments is not yet identified. The cDNA coding for Fc epsilon R II has been cloned and functionally expressed. The predicted amino acid sequence reveals no homology between human and rodent IgE-BFs indicating that they are unrelated molecules.
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    ABSTRACT: Summary There is mounting evidence that FceRII (CD23) and its soluble fragments (IgE-binding factors (BFs) or soluble CD23) have pleiotropic activities . IgE-BFs are formed mainly by the proteolytic cleavage of surface FceRII ; they are first released as 37- and 33-kD unstable molecules that are subsequently transformed into 25-kD IgE-BFs. In this study, purified and radioiodinated 37-kD IgE-BFs as well as 45-kD FceRII were used as substrates to identify the proteases leading to the formation of 25-kD IgE-BFs. These substrates generate 25-kD IgE-BFswhen incubated with several Fcc-RII-bearing cells, including CH01-7 cells (transfected with FceRIIcDNA) ; by contrast FceRII - cells, including CHO control cells, have no effect . Highly purified unlabeled native 37-kD and recombinant 29-kD IgE-BFs also cleave labeled 45-kD FceRII into 25-kD IgE-BFs . The proteolytic activity of these purified IgE-BFs is specifically removed by immunoprecipitation with an antibody against IgE-BFs . These data strongly suggest that FceRII and some of its soluble fragments play an active role in the proteolytic mechanism generating IgE-BFs. They are supported by the observation that IgE-BFs released by CHOl-7 cells are cleaved exactly at the same sites as B cell-derived IgE-BFs. Taken collectively, the results are compatible with an autoproteolytic process.
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