Structure and expression of the mb‐1 transcript in human lymphoid cells

• Published in: Clinical and experimental immunology Vol. 90; no. 1; pp. 141 - 146
• Main Authors: LEDUC, I., PREUD'HOMME, J.‐L., COGNÉ, M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-10-1992; Blackwell
• Subjects: Amino Acid Sequence; Antigens, CD; B cell specific expression; B-Lymphocytes - cytology; B-Lymphocytes - physiology; Base Sequence; Biological and medical sciences; CD79 Antigens; cDNA; Cell Differentiation; Cloning, Molecular; Fundamental and applied biological sciences. Psychology; Gene Expression; Genes, Immunoglobulin; human mb‐1; Humans; Immunoglobulin Heavy Chains - genetics; Immunoglobulin Light Chains - genetics; Membrane Glycoproteins - genetics; membrane immunoglobulin; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Receptors, Antigen, B-Cell - genetics; RNA, Messenger - genetics; Sequence Alignment; Human; Lymphoid cell; Membrane protein; Messenger RNA; Complementary DNA; Gene; Cell population; Nucleotide sequence; Gene product; Gene expression; Precursor
• ISSN: 0009-9104; 1365-2249
• DOI: 10.1111/j.1365-2249.1992.tb05846.x

SUMMARY
The mb‐1 gene encodes a protein associated with membrane‐bound immunoglobulins (mlg) and it has been suggested that it may play a role in signal iransduction. Using a murine probe, we cloned a human complementary DNA homologous to the murine mb‐1 sequence. Its complete sequence is in full agreement with a recently published human cDNA sequence but differs from a previously reported partial sequence. We studied mb‐1 expression in human cells at various maturation stages. Large amounts of a single 1–4 kb transcript were detectable in B cell lines carrying mlg of the μ, γ, α1 or α2 isotype. The mb‐1 mRNA was also expressed in prc‐B cells and in cells expressing truncated membrane fi chains devoid of associated light chains. Only trace amounts ol 'mb‐1 mRNA were found in tissue samples containing numerous plasma cells, while no mRNA was delected in several plasmacytoma cell lines, indicating that expression is shut down in plasma cells. No signal was found in T cells or in non‐lymphoid tissues. Altogether, these results show that the human mb‐1 gene is expressed in prc‐B cells and B lymphocytes, regardless of the isotype of the mlg heavy chain and is no longer expressed in plasma cells.