Abstract
Our knowledge of the immune system in the early vertebrates, the Agnatha, and the molecules involved in their immune reactions is fragmentary. By serendipity we discovered a cDNA clone in a library made from gut poly(A)+RNA of the sea lamprey, Petromyzon marinus (Pema), that translates into the SREG (SRCR-EGF, see below) protein which resembles cell-membrane proteins of mammalian immune cells. The putative translated product is a type-I integral membrane glycoprotein which contains two scavenger receptor Cys-rich (SRCR) domains flanking five epidermal growth factor (EGF)-like repeats. The two SRCR domains are closely related to CD6 (expressed on human lymphocytes), WC1 (expressed on mammalian CD4-CD8(-)-gamma delta T cells) and M130 (expressed on human macrophages). The Pema-SREG may therefore be involved in intercellular contacts and cell activation or differentiation in the immune system. It is thus a potential marker that can be used to investigate the lamprey immune system.
MeSH terms
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Amino Acid Sequence
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Animals
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Antigens, CD / biosynthesis
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Antigens, CD / chemistry
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Antigens, Differentiation, T-Lymphocyte / biosynthesis
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Antigens, Differentiation, T-Lymphocyte / chemistry
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Base Sequence
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Cell Membrane / immunology
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Cloning, Molecular
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Consensus Sequence
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Cysteine
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DNA, Complementary / metabolism
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Epidermal Growth Factor / chemistry
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Gene Library
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Humans
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Lampreys / genetics*
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Macrophages / immunology
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Mammals
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Membrane Glycoproteins / biosynthesis
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Membrane Glycoproteins / chemistry
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Membrane Glycoproteins / genetics
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Membrane Proteins*
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Molecular Sequence Data
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Phylogeny
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Protein Biosynthesis
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Receptors, Immunologic / biosynthesis*
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Receptors, Immunologic / chemistry
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Receptors, Immunologic / genetics*
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Receptors, Lipoprotein*
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Receptors, Scavenger
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Recombinant Proteins / biosynthesis
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Recombinant Proteins / chemistry
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Scavenger Receptors, Class B
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Sequence Homology, Amino Acid
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T-Lymphocytes / immunology
Substances
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Antigens, CD
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Antigens, Differentiation, T-Lymphocyte
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CD6 antigen
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DNA, Complementary
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Membrane Glycoproteins
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Membrane Proteins
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Receptors, Immunologic
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Receptors, Lipoprotein
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Receptors, Scavenger
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Recombinant Proteins
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Scarb1 protein, mouse
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Scavenger Receptors, Class B
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Epidermal Growth Factor
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Cysteine