title: Isolation and characterization of the two giant secretory proteins in salivary gland of Chironomus tentans.
abstract: The two giant secretory proteins, sp-Ia and sp-Ib, in salivary-gland cells of the larva of the fly Chironomus tentans, were isolated by preparative gel electrophoresis and characterized chemically. Their amino acid compositions are dominated by polar amino acids, with about 30% of basic amino acid residues. Crossed immunoelectrophoresis of sp-Ia and sp-Ib provided evidence that they share antigenic determinants. They also have major methionine-containing tryptic peptides in common. CNBr cleavage of sp-Ib gives a small number of low-Mr fragments, indicating that this protein has a repetitive structure.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002683:Chironomidae / Q000032:analysis*; D002850:Chromatography, Gel; D003488:Cyanogen Bromide; D004175:Diptera / Q000032:analysis*; D004587:Electrophoresis, Agar Gel; D007123:Immunoelectrophoresis, Two-Dimensional; D019476:Insect Proteins; D010446:Peptide Fragments / Q000032:analysis; D012469:Salivary Glands / Q000032:analysis; D012471:Salivary Proteins and Peptides / Q000276:immunology / Q000302:isolation & purification*; D014357:Trypsin
chemical_list: D000596:Amino Acids; D019476:Insect Proteins; D010446:Peptide Fragments; D012471:Salivary Proteins and Peptides; D014357:Trypsin; D003488:Cyanogen Bromide