Secretion of sulfated and nonsulfated forms of parathyroid chromogranin A (secretory protein-I)

• Published in: The Journal of biological chemistry Vol. 265; no. 6; pp. 3012 - 3016
• Main Authors: Gorr, S U, Cohn, D V
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 25.02.1990; American Society for Biochemistry and Molecular Biology
• Subjects: 550201 - Biochemistry- Tracer Techniques; AMINO ACIDS; ANIMALS; Autoradiography; BASIC BIOLOGICAL SCIENCES; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; BIOASSAY; BIOCHEMISTRY; Biological and medical sciences; BIOLOGICAL PATHWAYS; BODY; Calcium-Binding Proteins - biosynthesis; Calcium-Binding Proteins - isolation & purification; Calcium-Binding Proteins - metabolism; CARBOXYLIC ACIDS; CELL CONSTITUENTS; Cell physiology; CHEMISTRY; Chromogranin A; Chromogranins - biosynthesis; Chromogranins - isolation & purification; Chromogranins - metabolism; CYTOPLASM; Cytoplasmic Granules - metabolism; DAYS LIVING RADIOISOTOPES; DIAGNOSTIC TECHNIQUES; DOMESTIC ANIMALS; DOSE-RESPONSE RELATIONSHIPS; ELECTROPHORESIS; Electrophoresis, Polyacrylamide Gel; ENDOCRINE GLANDS; EVEN-ODD NUCLEI; Fundamental and applied biological sciences. Psychology; GLANDS; GLYCOPROTEINS; HYDROGEN COMPOUNDS; IMMUNOASSAY; IMMUNOLOGY; IN VITRO; In Vitro Techniques; ISOTOPE APPLICATIONS; ISOTOPES; Kinetics; LIGHT NUCLEI; LYSINE; Lysine - metabolism; MAMMALS; Molecular and cellular biology; MOLECULAR WEIGHT; Nerve Tissue Proteins - metabolism; NUCLEI; ORGANIC ACIDS; ORGANIC COMPOUNDS; ORGANS; OXYGEN COMPOUNDS; parathyroid; PARATHYROID GLANDS; Parathyroid Glands - metabolism; pigs; PROTEINS; RADIOASSAY; RADIOIMMUNOASSAY; RADIOIMMUNODETECTION; RADIOIMMUNOLOGY; RADIOISOTOPES; SECRETION; Secretion. Exocytosis; SULFATES; Sulfates - metabolism; SULFUR 35; SULFUR COMPOUNDS; SULFUR ISOTOPES; Sulfur Radioisotopes; Sulfuric Acids - analysis; SWINE; TRACER TECHNIQUES; Tritium; TRITIUM COMPOUNDS; VERTEBRATES; Calcium; Secretion; Glycoproteins; Pig; Dose activity relation; Sulfatation; Vertebrata; Regulation(control); Mammalia; Chromogranin; Parathyroid glands; Artiodactyla; Ungulata; Quantitative analysis
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)39725-X

Chromogranin A (secretory protein-I) is an acidic, sulfated glycoprotein found in secretory granules of most endocrine cells but not in exocrine or epithelial cells. Parathyroid chromogranin A is sulfated on tyrosine residues, whereas adrenal chromogranin A appears to be sulfated mainly on oligosaccharide residues. Chromogranin B, on the other hand, is tyrosine-sulfated in the bovine adrenal whereas this protein is absent from the parathyroid. The role of this tissue- or species-specific sulfation of chromogranin is not known. Tyrosine sulfation is a common post-translational modification of proteins in the exocytotic pathway and has been suggested to play a role in the sorting or intracellular transport of secretory proteins. To test this, porcine parathyroid tissue slices were metabolically labeled with 35SO4 and [3H]Lys, and the tissue and incubation medium analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblotting, and immunoprecipitation with chromogranin A-specific antiserum or by radioimmunoassay for parathormone. Secretion of total and 3H-labeled chromogranin A was about 3- and 7-fold higher, respectively, at 0.5 mM than at 3.0 mM Ca2+, and secretion of 35SO4-labeled chromogranin A was 67-fold higher. This indicates that either sulfated chromogranin A is directed primarily to the Ca2+-regulated pathway or that sulfation occurs following sorting to this pathway. Sodium chlorate (1-10 mM) inhibited sulfation in a dose-dependent manner by up to 95% but it had no effect on the onset or rate of chromogranin A secretion. These data indicate that regulated secretion of parathyroid chromogranin A does not require sulfation of tyrosine residues.