Molecular cloning of the lymphocyte activation marker Blast-1.
Blast-1 is an early activation-associated glycoprotein expressed on the surface of human lymphocytes. Here we report the isolation and analysis of a cDNA encoding Blast-1. The translated sequence of the Blast-1 cDNA contains a hydrophobic putative signal peptide and a hydrophobic carboxyl terminus devoid of charged residues. The sequence also contains five N-linked glycosylation sites, the utilization of which was confirmed by the shift in relative mol. wt of Blast-1 upon digestion with N-glycosidase F. The translated sequence reveals that Blast-1 is related to members of the immunoglobulin superfamily, especially to CD4 and MHC class II molecules. The homology to these proteins is greatest in their amino termini where they demonstrate 30-32% identity. This region of Blast-1 also demonstrated 25% identity to a V kappa sequence. Considering conservative amino acid substitutions this homology to CD4, MHC class II and V kappa becomes 60, 49 and 48%, respectively.
Staunton
D E
DE
Department of Pathology, Tufts University School of Medicine, Boston, MA 02111.
Thorley-Lawson
D A
DA
D000595:Amino Acid Sequence; D000944:Antigens, Differentiation, B-Lymphocyte / Q000235:genetics*; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA / Q000302:isolation & purification; D004262:DNA Restriction Enzymes; D005796:Genes; D006801:Humans; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D000944:Antigens, Differentiation, B-Lymphocyte; D004247:DNA; D004262:DNA Restriction Enzymes