Two Integral Membrane Proteins Located in the Cis-Middle and Trans-Part of the Golgi System Acquire Sialylated N-Linked Carbohydrates and Display Different Turnovers and Sensitivity to cAMP-Dependent Phosphorylation

• Published in: The Journal of cell biology Vol. 105; no. 1; pp. 215 - 227
• Main Authors: Yuan, Lydia, Barriocanal, Javier G., Bonifacino, Juan S., Sandoval, Ignacio V.
• Format: Journal Article
• Language: English
• Published: New York, NY Rockefeller University Press 01.07.1987; The Rockefeller University Press
• Subjects: Animals; Antibodies; Antibodies, Monoclonal - immunology; Basophils; Biological and medical sciences; Carbohydrate Metabolism; Cell Line; Cell lines; Cell membranes; Cell structures and functions; Cells; Fluorescent Antibody Technique; Fundamental and applied biological sciences. Psychology; Glycoproteins - immunology; Glycoproteins - metabolism; Golgi apparatus; Golgi Apparatus - metabolism; Kidney; Leukemia, Experimental - pathology; Membrane Glycoproteins; Membrane proteins; Membrane Proteins - immunology; Membrane Proteins - metabolism; Microtubules; Molecular and cellular biology; N-Acetylneuraminic Acid; Organelles; Phosphorylation; Phosphoserine - metabolism; Protein Kinases - metabolism; Protein Precursors - metabolism; Protein Processing, Post-Translational; Rats; Sialic Acids - metabolism; Cell culture; Phosphorylation; Membrane protein; Rat; Immunocytochemistry; Leukemia; Rodentia; Cyclic AMP; Monoclonal antibody; Kidney; Golgi apparatus; Vertebrata; Mammalia; Transmission electron microscopy; Ultrastructure; Carbohydrate
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.105.1.215

The localization and chemical characteristics of two Golgi integral membrane proteins (GIMPs) have been studied using monoclonal antibodies. The two proteins are segregated in different parts of the Golgi system and whereas GIMPc(130 kD) is located in the cis and medial cisternae, GIMPt(100 kD) is confined in the trans-most cisterna and trans-tubular network. Both GIMPs are glycoproteins that contain N- and O-linked carbohydrates. The N-linked carbohydrates were exclusively of the complex type. Although excluded from the trans-side of the Golgi system, where sialylation is believed to occur, GIMPcacquires sialic acid in both its N- and O-linked carbohydrates. Sialic acid was also detected in the N-linked carbohydrates of GIMPt. GIMPcis apparently phosphorylated in the luminal domain in vivo. Phosphorylation occurred exclusively on serine and was stimulated by dibutyryl cyclic AMP. GIMPcand GIMPtdisplayed half-lives of 20 and 9 h, respectively.