We found that a variety of cholecystokinin (CCK) receptor ligands bind to bovine serum albumin (BSA). This binding was rapid, fully reversible, temperature independent, of low affinity, and specific for BSA; it depended on the concentration of BSA, the chemical structure of the ligand, and the chemical composition of the incubation medium. BSA also decreased the binding of I-125-labeled CCK octapeptide (I-125-CCK-8) to CCK receptors on pancreatic acini and membranes but increased the potency with which CCK-8 inhibited binding of I-125-CCK-8. These counterintuitive findings appeared to result from BSA altering the affinities of CCK-8 for different affinity states of the pancreatic CCK receptor. An alternate hypothesis is that BSA increased the efficacy of CCK-8 such that it bound to receptors and also ca;sed biochemical changes in other receptors that reduced their ability to bind I-125-CCK-8. BSA enhanced the ability of CCK-8 to stimulate amylase secretion from pancreatic acini and to cause contraction of dispersed gastric smooth muscle cells. Thus, CCK can bind to BSA, and the BSA-CCK complex has substantially different activities from the free, uncomplexed hormone.
MODULATION OF CHOLECYSTOKININ ACTIVITY BY ALBUMIN / S. C., Huang; V. D., Talkad; K. P., Fortune; S., Jonnalagadda; Severi, Carola; DELLE FAVE, Gianfranco; J. D., Gardner. - In: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA. - ISSN 0027-8424. - 92:22(1995), pp. 10312-10316. [10.1073/pnas.92.22.10312]
MODULATION OF CHOLECYSTOKININ ACTIVITY BY ALBUMIN
SEVERI, Carola;DELLE FAVE, Gianfranco;
1995
Abstract
We found that a variety of cholecystokinin (CCK) receptor ligands bind to bovine serum albumin (BSA). This binding was rapid, fully reversible, temperature independent, of low affinity, and specific for BSA; it depended on the concentration of BSA, the chemical structure of the ligand, and the chemical composition of the incubation medium. BSA also decreased the binding of I-125-labeled CCK octapeptide (I-125-CCK-8) to CCK receptors on pancreatic acini and membranes but increased the potency with which CCK-8 inhibited binding of I-125-CCK-8. These counterintuitive findings appeared to result from BSA altering the affinities of CCK-8 for different affinity states of the pancreatic CCK receptor. An alternate hypothesis is that BSA increased the efficacy of CCK-8 such that it bound to receptors and also ca;sed biochemical changes in other receptors that reduced their ability to bind I-125-CCK-8. BSA enhanced the ability of CCK-8 to stimulate amylase secretion from pancreatic acini and to cause contraction of dispersed gastric smooth muscle cells. Thus, CCK can bind to BSA, and the BSA-CCK complex has substantially different activities from the free, uncomplexed hormone.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.