title: Molecular cloning of bovine mb-1 cDNA.
abstract: Ig-alpha of the B-cell antigen receptor complex forms a heterodimeric structure with Ig-beta on the plasma membrane of B-lymphocytes and is apparently involved in signal transduction during the activation of B-cells. Bovine leukemia virus (BLV) is predominantly a B-cell tropic retrovirus, which induces persistent lymphocytosis and leukemia/lymphoma of B-cell lineage in cattle. To understand the mechanisms of proliferation and tumorigenesis of bovine B-cells that are associated with BLV infection, we investigated the B-cell antigen receptor complex, especially bovine mb-1 encoding the bovine Ig-alpha protein. We isolated a full-length bovine mb-1 cDNA clone encoding 223 amino acid residues. The deduced amino acid sequence of the bovine mb-1 showed extensive homology with those of human and murine mb-1. The cytoplasmic tail of the bovine mb-1 also contained a consensus motif (D/E-X7-D/E-X2-L/I-X7-Y-X2-L/I) that may interact with the SH2 domain of src-type kinase. Interestingly, a similar consensus sequence motif was found in the BLV gp30env, although the overall sequence similarity between bovine mb-1 and BLVgp30 was not significant. Furthermore, elevated levels of mb-1 transcript were detected in various bovine leukemia/lymphoma cell lines. These results indicated that the proliferation of B-cells associated with BLV-infection may be related to abnormal signal transduction through the B-cell antigen receptor complex.
authors.affiliation: Department of Veterinary Internal Medicine, Faculty of Agriculture, University of Tokyo, Japan.
authors.forename: H Y
authors.initials: HY
authors.lastname: Youn
authors.forename: R
authors.initials: R
authors.lastname: Goitsuka
authors.forename: H
authors.initials: H
authors.lastname: Kato
authors.forename: D Y
authors.initials: DY
authors.lastname: Mason
authors.forename: T
authors.initials: T
authors.lastname: Watari
authors.forename: H
authors.initials: H
authors.lastname: Tsujimoto
authors.forename: A
authors.initials: A
authors.lastname: Hasegawa
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000502:physiology*; D001483:Base Sequence; D015152:Blotting, Northern; D019556:COS Cells; D002417:Cattle; D003001:Cloning, Molecular; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D001909:Leukemia Virus, Bovine / Q000235:genetics*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D011947:Receptors, Antigen, B-Cell / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014407:Tumor Cells, Cultured
chemical_list: D012333:RNA, Messenger; D011947:Receptors, Antigen, B-Cell