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Complementary methods provide evidence for the expression of CXCR7 on human B cells

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Publication date 2012
Author Humpert Marie Luise, Tzouros Manuel, Thelen Sylvia, Bignon Alexandre, Bignon Alexandre, Levoye Angélique, Arenzana-Seisdedos Fernando, Balabanian Karl, Balabanian Karl, Bachelerie Françoise, Bachelerie Françoise, Langen Hanno, Thelen Marcus,
Project Conventional and atypical chemokine receptors: different mechanisms of function and common responses
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Original article (peer-reviewed)

Journal Proteomics
Volume (Issue) 12(12)
Page(s) 1938 - 1948
Title of proceedings Proteomics
DOI 10.1002/pmic.201100581

Abstract

PTMs of extracellular domains of membrane proteins can influence antibody binding and give rise to ambivalent results. Best proof of protein expression is the use of complementary methods to provide unequivocal evidence. CXCR7, a member of the atypical chemokine receptor family, mainly functions as scavenger for the chemokines CXCL12 and CXCL11. The expression of CXCR7 on nonhematopoietic cells and neoplasms is widely accepted, however, its expression on leukocytes was recently challenged. To solve the dissent, we thoroughly analyzed the expression of CXCR7 on human B cells. We validated the efficiency of different epitope-specific monoclonal antibodies to detect CXCR7 on transfected cells and primary human B cells. The specificity of the used antibodies was further confirmed by an experimentally independent double labeling approach. Examination of CXCR7-dependent scavenging of fluorescent-labeled CXCL12 revealed functional expression of the receptor on human B cells. Moreover, real-time PCR analysis of CXCR7 mRNA showed the presence of transcripts in human leukocytes. Finally, two CXCR7-specific peptides were identified by MS in immunoprecipitates from primary human B cells. Thus, we present a strategy based on combined proteomic and functional approaches that can be used to solve dissents on protein expression, i.e. demonstrating the expression of CXCR7 on human leukocytes. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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