The novel variants of mb-1 and B29 transcripts generated by alternative mRNA splicing.
The Ig-alpha/Ig-beta heterodimers encoded by mb-1 and B29 genes, respectively, are crucial for the constitution of the B-cell receptor (BCR). We report here novel variants of mb-1 and B29 transcripts produced by alternative mRNA splicing. The proteins encoded by these variants are predicted to conserve transmembrane and cytoplasmic portions of Ig-alpha and Ig-beta but lack a part of the extracellular portions containing cysteine residues which are required for intramolecular and intermolecular S-S bonds. Transfection studies revealed that the variant mb-1 and B29 did not contribute to the BCR expression on cell surfaces. Although peripheral B cells contain small amounts of the variant mb-1 and B29 transcripts, treatment with an anti-IgM antibody, LPS or IL-4 induces a significant increase in amounts of the variant transcripts. These observations suggest that B-cell activation induces alternative splicing of mb-1 and B29 transcripts which encode proteins unable to constitute the BCR.
Koyama
M
M
First Department of Internal Medicine, University of Tokyo, Japan.
Nakamura
T
T
Higashihara
M
M
Herren
B
B
Kuwata
S
S
Shibata
Y
Y
Okumura
K
K
Kurokawa
K
K
D017398:Alternative Splicing; D015703:Antigens, CD / Q000235:genetics*; D001402:B-Lymphocytes / Q000276:immunology; D001483:Base Sequence; D051925:CD79 Antigens; D002478:Cells, Cultured; D015870:Gene Expression; D006801:Humans; D008213:Lymphocyte Activation; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D011506:Proteins / Q000235:genetics*; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000032:analysis / Q000737:chemistry; D011947:Receptors, Antigen, B-Cell / Q000235:genetics*; D014162:Transfection
D015703:Antigens, CD; C091247:BCAP31 protein, human; D051925:CD79 Antigens; C497881:CD79A protein, human; D008565:Membrane Proteins; D011506:Proteins; D012333:RNA, Messenger; D011947:Receptors, Antigen, B-Cell