BCMAp: an integral membrane protein in the Golgi apparatus of human mature B lymphocytes

BCMA is a human gene expressed preferentially in mature B lymphocytes as a 1.2 kb mRNA, which encodes a 184 amino acid peptide (BCMAp). The study of BCMA mRNA expression, using human malignant B cell lines characteristic of different stages of B lymphocyte differentiation, demonstrated that the BCMA...

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Bibliographic Details
Published in:International immunology 1995-07, Vol.7 (7), p.1093-1106
Main Authors: Gras, Marie-Pierre, Laâbi, Yacine, Linares-Cruz, Gustavo, Blondel, Marie-Odile, Rigaut, Jean-Paul, Brouet, Jean-Claude, Leca, Gérald, Haguenauer-Tsapis, Rosine, Tsapis, Andréas
Format: Article
Language:English
Subjects:
B cell
B-Cell Maturation Antigen
B-Lymphocytes - chemistry
Cell Compartmentation
Fluorescent Antibody Technique
Golgi apparatus
Golgi Apparatus - chemistry
Golgi Apparatus - immunology
Humans
maturation
Membrane Glycoproteins - chemistry
Membrane Glycoproteins - genetics
Membrane Proteins - chemistry
Membrane Proteins - genetics
Microscopy, Confocal
Microsomes - chemistry
Protein Conformation
Receptors, Tumor Necrosis Factor
RNA, Messenger - chemistry
transmembrane protein
Tumor Cells, Cultured
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Summary:BCMA is a human gene expressed preferentially in mature B lymphocytes as a 1.2 kb mRNA, which encodes a 184 amino acid peptide (BCMAp). The study of BCMA mRNA expression, using human malignant B cell lines characteristic of different stages of B lymphocyte differentiation, demonstrated that the BCMA mRNA is absent in the pro-B lymphocyte stage. It is expressed faintly at the pre-B cell stage and its expression increases with B lymphocyte maturation. Polyclonal antibodies were used to show, by cellular fractionation and immunoprecipitation, that BCMAp is a non-glycosylated integral membrane protein. Furthermore, BCMAp inserts, in vitro, into canine microsomes, as a type I integral membrane protein. Cell surface labeling showed that BCMAp is not expressed in the plasma membrane of mature B lymphocytes. Immunofluorescence studies revealed that BCMAp lies in a cap-like structure near the nucleus, that was identified as the Golgi apparatus by co-localization of BCMAp with CTR433, a marker of the medial cisternae of the Golgi apparatus. Confocal scanning laser microscopy of U266 plasma cells labeled with markers of various Golgi apparatus subcompartments strongly suggests that BCMAp is located in the cis part of the Golgi apparatus. Thus, BCMAp is the first Golgi resident protein with a tissue specificity and whose expression is linked to the stage of differentiation of B lymphocytes. The location of BCMAp in the Golgi apparatus and its high expression in plasmocytes (secreting large amounts of Ig) suggest that BCMAp is implicated in the intracellular traffic of Ig.
ISSN:0953-8178
1460-2377
DOI:10.1093/intimm/7.7.1093