ARTICLE

PROTEIN SYNTHESIS, STORAGE, AND DISCHARGE IN THE PANCREATIC EXOCRINE CELL

Lucien G. Caro Ph.D.¹ and George E. Palade M.D.¹

¹ From The Rockefeller Institute.

Dr. Caro's present address is Biology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee

The synthesis, intracellular transport, storage, and discharge of secretory proteins in and from the pancreatic exocrine cell of the guinea pig were studied by light- and electron microscopical autoradiography using DL-leucine-4,5-H³ as label. Control experiments were carried out to determine: (a) the length of the label pulse in the blood and tissue after intravenous injections of leucine-H³; (b) the amount and nature of label lost during tissue fixation, dehydration, and embedding. The results indicate that leucine-H³ can be used as a label for newly synthesized secretory proteins and as a tracer for their intracellular movements. The autoradiographic observations show that, at 5 minutes after injection, the label is localized mostly in cell regions occupied by rough surfaced elements of the endoplasmic reticulum; at 20 minutes, it appears in elements of the Golgi complex; and after 1 hour, in zymogen granules. The evidence conclusively shows that the zymogen granules are formed in the Golgi region by a progressive concentration of secretory products within large condensing vacuoles. The findings are compatible with an early transfer of label from the rough surfaced endoplasmic reticulum to the Golgi complex, and suggest the existence of two distinct steps in the transit of secretory proteins through the latter. The first is connected with small, smooth surfaced vesicles situated at the periphery of the complex, and the second with centrally located condensing vacuoles.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

• Powell, K. (2005). Sugars sprinkled onto proteins in the Golgi. JCB 169: 19-19 [Full Text]  
• Wells, W. A. (2005). A pathway for secretion. JCB 168: 525-525 [Full Text]  
• Dvorak, A. M., Morgan, E. S., Lichtenstein, L. M., Weller, P. F., Schleimer, R. P. (2000). RNA Is Closely Associated with Human Mast Cell Secretory Granules, Suggesting a Role(s) for Granules in Synthetic Processes. J. Histochem. Cytochem. 48: 1-12 [Abstract] [Full Text]  
• Qu-Hong, , Brown, L. F., Dvorak, H. F., Dvorak, A. M. (1997). Ultrastructural Immunogold Localization of Osteopontin in Human Gastric Mucosa. J. Histochem. Cytochem. 45: 21-34 [Abstract] [Full Text]  
• Palade, G (1975). Intracellular aspects of the process of protein synthesis. Science 189: 347-358  
• Hanks, C.T., Chaudhry, A.P. (1971). Radioautographic Evidence of 3H-Tryptophan Incorporation in Secretory Cells of Rat Submandibular Glands. JDR 50: 1626-1630 [Abstract]  
• Tiber, A. (1971). Radioautographic and Histochemical Study of Protein Synthesis in the Hamster Submandibular Gland. JDR 50: 837-845 [Abstract]  
• Rasmussen, H. (1970). Cell Communication, Calcium Ion, and Cyclic Adenosine Monophosphate. Science 170: 404-412 [Abstract]  
• Fetter, A.W., Capen, C.C. (1970). Ultrastructural Evaluation of Thyroid Parafollicular Cells of Pigs with Naturally Occurring Atrophic Rhinitis. Veterinary Pathology 7: 171-185 [Abstract]  
• Tani, E., Kawamura, Y., Ametani, T., Handa, H., Imura, H., Kato, Y. (1969). Immunocytochemistry of Acidophil. Arch Neurol 20: 634-643 [Abstract]  
• Leeson, C. R., Leeson, T. S. (1968). Fine Structure and Possible Secretory Mechanism of Rat Palatine Glands. JDR 47: 653-662 [Abstract]  
• Steiner, D. F., Cunningham, D., Spigelman, L., Aten, B. (1967). Insulin Biosynthesis: Evidence for a Precursor. Science 157: 697-700 [Abstract]  
• Duvall, A. J. III, Rhodes, V. T. (1967). Reissner's Membrane: An Ultrastructural Study. Arch Otolaryngol Head Neck Surg 86: 143-151 [Abstract]  
• Askonas, B. A., Williamson, A. R. (1967). Biosynthesis and Assembly of Immunoglobulin G. Cold Spring Harb Symp Quant Biol 32: 223-231 [Abstract]  
• Melchers, F., Knopf, P. M. (1967). Biosynthesis of the Carbohydrate Portion of Immunoglobulin Chains: Possible Relation to Secretion. Cold Spring Harb Symp Quant Biol 32: 255-262 [Abstract]  
• Palade, G. E. (1966). Structure and Function at the Cellular Level. JAMA 198: 815-825 [Abstract]  
• Ross, R. (1966). The Ultrastructure of Fibrogenesis. JDR 45: 449-462  
• Mangan, J., Miki-Noumura, T., Gross, P. R. (1965). Protein Synthesis and the Mitotic Apparatus. Science 147: 1575-1578 [Abstract]  

Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents