Molecular cloning of Ly-1, a membrane glycoprotein of mouse T lymphocytes and a subset of B cells: molecular homology to its human counterpart Leu-1/T1 (CD5).
We report the isolation of cDNA clones of the mouse lymphocyte differentiation antigen Ly-1. One of these cDNA clones was confirmed to be full-length by DNA sequencing and by expression of Ly-1 by L cells transfected with this clone. Analysis of the predicted amino acid sequence indicated that the Ly-1 polypeptide is synthesized with a 23 amino acid leader and that the mature protein consists of an amino-terminal region of 347 amino acids, a transmembrane sequence of 30 residues, and a carboxyl-terminal region of 94 amino acids. The amino-terminal region appears to be divided into two subregions by a threonine- and proline-rich sequence of 23 amino acids that is highly conserved between Ly-1 and its human homologue Leu-1 (CD5) in position and amino acid composition. The first amino-terminal subregion of 111 amino acids is predicted to be arranged in a beta-pleated sheet structure of six strands. The entire amino-terminal region is rich in cysteine, with all of its 22 cysteine residues conserved between Ly-1 and Leu-1. The carboxyl-terminal region has no cysteines. Ly-1 and Leu-1 are 63% identical, with a gradient of identical residues from 43% for the first amino-terminal subregion to 58% for the second amino-terminal subregion and 90% for the carboxyl-terminal region. The predicted secondary structure of the first amino-terminal subregion and identities of certain conserved residues among most members of the immunoglobulin gene superfamily suggest that Ly-1 and Leu-1 are distant members of this family.
D000595:Amino Acid Sequence; D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte; D000950:Antigens, Ly / Q000235:genetics*; D000954:Antigens, Surface / Q000235:genetics*; D001402:B-Lymphocytes / Q000145:classification / Q000276:immunology*; D001483:Base Sequence; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D005784:Gene Amplification; D006801:Humans; D051379:Mice; D009693:Nucleic Acid Hybridization; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D013601:T-Lymphocytes / Q000276:immunology*
D000945:Antigens, Differentiation, T-Lymphocyte; D000950:Antigens, Ly; D000954:Antigens, Surface; D004262:DNA Restriction Enzymes