Temperature dependence of high-affinity CCK receptor binding and CCK internalization in rat pancreatic acini

Journal Article · Fri Apr 01 04:00:00 EST 1988 · American Journal of Physiology; (USA)

OSTI ID:6749530

Williams, J A; Bailey, A C; Roach, E ^[1]

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1. Mount Zion Hospital and Medical Center, San Francisco (USA) Univ. of California, San Francisco (USA)

{sup 125}I-labeled cholecystokinin (CCK) binding and internalization were studied as a function of temperatures in isolated rat pancreatic acini. At 37{degree}C, acini readily bound and degraded {sup 125}I-CCK. When labeled hormone binding was inhibited by increasing amounts of unlabeled CCK, competition-inhibition curves were biphasic, consistent with both high- (K{sub d}, 18 pM) and low-affinity (K{sub d}, 13 nM) binding sites. At 4{degree}C, acini bound only one-third as much {sup 125}I-CCK and degradation was essentially abolished. At 4{degree}C, CCK competition curves were consistent with a single class of low-affinity binding sites (K{sub d}, 19 nM). Internalization of {sup 125}I-CCK was evaluated by three washing procedures utilizing acid, base, and trypsin. All were shown to remove membrane-bound {sup 125}I-CCK, and this finding was validated for trypsin by electron microscope autotradiography. When internalization of {sup 125}I-CCK was evaluated as a function of the medium concentration of CCK, both high- and low-affinity components were observed. These results suggest that high-affinity CCK binding and CCK internalization are separate temperature-sensitive processes. Moreover, internalization is not uniquely associated with high-affinity binding.

• OSTI ID: 6749530
• Journal Information: American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 254:4; ISSN 0002-9513; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
AUTORADIOGRAPHY
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BODY
CHEMICAL REACTIONS
CROSS-LINKING
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
ELECTRON CAPTURE RADIOISOTOPES
ELECTRON MICROSCOPY
ENDOCRINE GLANDS
GLANDS
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPES
KINETICS
KININS
LIGANDS
MAMMALS
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
MICROSCOPY
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PANCREAS
PEPTIDES
POLYMERIZATION
POLYPEPTIDES
PROTEINS
RADIOISOTOPES
RATS
REACTION KINETICS
RECEPTORS
RODENTS
TEMPERATURE DEPENDENCE
TRANSMISSION ELECTRON MICROSCOPY
VERTEBRATES