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Binding, internalization, and processing of bombesin by rat pancreatic acini
- Source :
- The American journal of physiology. 261(1 Pt 1)
- Publication Year :
- 1991
-
Abstract
- The binding and subsequent fate of 125I-labeled bombesin was studied in rat pancreatic acini. At both 37 degrees C and 4 degrees C binding occurred to a single saturable site, with Kd equal to 1.7 nM. The amount of steady-state tracer binding was reduced at 4 degrees C (5.7%/mg protein) compared with 37 degrees C (8.7%/mg), with a similar relative change in calculated binding capacity. With the use of an acid wash procedure to remove surface bound ligand, 55% of cell-associated 125I-bombesin was internalized in the steady state at 37 degrees C but only 5% at 4 degrees C. Preincubation at 4 degrees C followed by an increase to 37 degrees C led to rapid internalization of bound bombesin, which was blocked by the metabolic inhibitor antimycin. 125I-bombesin was found to be degraded by two acinar systems. One was not related to receptor binding but could be inhibited with bacitracin. The other occurred after internalization and was partially blocked with chloroquine. Thus, after binding, bombesin is internalized, and the degradation products are released from the cell. Exposure to bombesin is also accompanied by a subsequent decrease in cell surface binding (54% after 1 h exposure to 100 nM bombesin), suggesting that the bombesin receptor may also be internalized in a ligand-dependent manner.
- Subjects :
- Male
medicine.medical_specialty
Physiology
media_common.quotation_subject
Neuropeptide
Down-Regulation
Biology
digestive system
complex mixtures
Binding, Competitive
chemistry.chemical_compound
Acinus
Physiology (medical)
Internal medicine
medicine
Animals
Internalization
Pancreas
Chromatography, High Pressure Liquid
media_common
Hepatology
Gastroenterology
Temperature
Bombesin
Rats, Inbred Strains
Ligand (biochemistry)
In vitro
Bombesin receptor
Rats
Receptors, Neurotransmitter
Receptors, Bombesin
Kinetics
Endocrinology
medicine.anatomical_structure
chemistry
Biophysics
Steady state (chemistry)
hormones, hormone substitutes, and hormone antagonists
Subjects
Details
- ISSN :
- 00029513
- Volume :
- 261
- Issue :
- 1 Pt 1
- Database :
- OpenAIRE
- Journal :
- The American journal of physiology
- Accession number :
- edsair.doi.dedup.....6ec05d18ecc603ad20525db2ae141cf4