title: High molecular weight forms of adrenocorticotropic hormone are glycoproteins.
abstract: Mouse pituitary tumor cells (AtT-20/D-16v) were incubated in medium containing [3H] glucosamine or [3H] mannose. By analyzing immunoprecipitates of cell extracts and culture medium it was shown that [3H] glucosamine and [3H] mannose were incorporated into all three high molecular weight forms of ACTH; label was not incorporated into Mr=4,500 ACTH (which is thought to be similar to the 39 amino acid polypeptide form of ACTH, alpha(1-39)). Based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis the apparent molecular weights of these glycoprotein forms of ACTH were 31,000, 23,000, and 13,000. Gel filtration in 6 M guanidine HCl indicated that the molecular weights of these forms of ACTH were substantially lower; sodium dodecyl sulfate-polyacrylamide gel electrophoresis has often been found to overestimate the molecular weight of glycoproteins. A significant fraction of the high molecular weight ACTH in tumor cell extracts binds to columns of concanavalin A-agarose and can be eluted with 0.2 M alpha-methyl-D-mannopyranoside; porcine alpha(1-39) does not bind to concanavalin A-agarose. High molecular weight glycoprotein ACTH can be detected in extracts of mouse and bovine pituitary by using concavalin A affinity chromatography.
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000096:biosynthesis; D002460:Cell Line; D005944:Glucosamine / Q000378:metabolism; D006023:Glycoproteins / Q000096:biosynthesis; D008239:Lysine / Q000378:metabolism; D008358:Mannose / Q000378:metabolism; D008970:Molecular Weight; D010911:Pituitary Neoplasms / Q000378:metabolism
chemical_list: D006023:Glycoproteins; D000324:Adrenocorticotropic Hormone; D008239:Lysine; D005944:Glucosamine; D008358:Mannose