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.

• Authors: B A Eipper, R E Mains, D Guenzi
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 251 Issue 13 Pg. 4121-6 (Jul 10 1976) ISSN: 0021-9258 [Print] United States
• PMID: 180016 (Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Glycoproteins
• Adrenocorticotropic Hormone
• Lysine
• Glucosamine
• Mannose

Topics

• Adrenocorticotropic Hormone (biosynthesis)
• Cell Line
• Glucosamine (metabolism)
• Glycoproteins (biosynthesis)
• Lysine (metabolism)
• Mannose (metabolism)
• Molecular Weight
• Pituitary Neoplasms (metabolism)