BIT, an immune antigen receptor-like molecule in the brain

• Published in: FEBS letters Vol. 411; no. 2; pp. 327 - 334
• Main Authors: Sano, Shin-ichiro, Ohnishi, Hiroshi, Omori, Akira, Hasegawa, Junko, Kubota, Misae
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 14.07.1997
• Subjects: Amino Acid Sequence; Animals; Antibodies, Monoclonal; Antigens, Differentiation; Base Sequence; Blotting, Northern; Brain - cytology; Brain - immunology; Brain - metabolism; Cells, Cultured; Cloning, Molecular; Immune antigen receptor-like molecule; Immunoblotting; Immunoglobulin superfamily; Laminin - metabolism; Membrane Glycoproteins; Molecular Sequence Data; Nerve Tissue Proteins - chemistry; Nerve Tissue Proteins - physiology; Neural Cell Adhesion Molecule L1; Neurite extension; Neurites - ultrastructure; Neurons - cytology; Phosphotyrosine - metabolism; Protein-Tyrosine Kinases - metabolism; Rat brain; Rats; Receptors, Immunologic - chemistry; Receptors, Immunologic - physiology; RNA, Messenger - analysis; Sequence Alignment; Signal Transduction - physiology; Tyrosine phosphorylation; TCR, T-cell receptor; IRS-1, insulin receptor substrate-1; Immune antigen receptor-like molecule; HEPES, N-2-hydroxyethylpiperazine- N′-ethanesulfonic acid; MHC, major histocompatibility complex; CHAPS, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate; PMSF, phenylmethylsulfonyl fluoride; Immunoglobulin superfamily; Tyrosine phosphorylation; TAM, tyrosine-based activation motif; Neurite extension; Rat brain; SH2, src homology 2
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/S0014-5793(97)00724-2

We previously found a brain-specific glycoprotein in the rat brain. It postnatally increases and is rich in the mature brain. We cloned cDNA of this protein. It is composed of a signal peptide, a V-type immunoglobulin domain, two C1-type immunoglobulin domains, a transmembrane segment and a cytoplasmic region containing two tyrosine-based activation motifs (TAM) that are variants of the antigen receptor signaling motifs. The overall structure is similar to those of immune antigen receptors. This molecule, BIT ( brain immunoglobulin-like molecule with TAMs), is a major endogenous substrates of brain tyrosine kinases in vitro. Cerebral cortical neurons could extend their neurites on BIT-coated substrate and anti-BIT monoclonal antibody specifically inhibited the effect. These findings and our recent study concerning BIT signal transduction mechanism suggest that BIT, an immune antigen receptor-like molecule of the brain, functions as a membrane signaling molecule that may participate in cell–cell interaction.