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Characteristics of binding of a low affinity, noncooperative insulin ((LeuB25)insulin) to IM-9 lymphocytes

Journal Article · · Endocrinology; (United States)
; ; ; ;
(Leu-B25)insulin is a low affinity insulin analog which does not increase the rate of dissociation of /sup 125/I-insulin from insulin receptors (i.e. does not display negative cooperativity). We have studied the characteristics of binding of this analog to IM-9 cultured lymphocytes, in order to determine the contribution of negative cooperativity to the curvilinear nature of Scatchard plots typical of insulin binding data. The affinity of (LeuB25)insulin for receptors was approximately 1% that of insulin, as determined by its ability to inhibit /sup 125/I-insulin binding. Monoiodinated preparations of insulin and of (LeuB25)insulin were produced, labeled in the tyrosine at position 14 of the A chain. These /sup 125/I-TyrA14-labeled species were used in all studies. Both native insulin and a serum containing antiinsulin receptor antibodies were equally potent at inhibiting binding of /sup 125/I-(LeuB25)insulin and /sup 125/I-native insulin, suggesting that they bind to the same population of receptors. Native insulin (100 ng/ml) increased the rate of dissociation of both /sup 125/I-insulin and /sup 125/I-(LeuB25)insulin. However, (LeuB25)insulin (2.5 micrograms/ml) did not increase the rates of dissociation of either /sup 125/I-insulin or /sup 125/I-(LeuB25)insulin (i.e. it did not display negative cooperativity). Competition curves and Scatchard plots were constructed using /sup 125/I-(LeuB25)insulin and unlabeled analog. Half-maximal inhibition of /sup 125/I-(LeuB25)insulin binding was seen at a (LeuB25)insulin concentration of approximately 500 ng/ml. More importantly, the Scatchard plot of these binding data was markedly curvilinear, as is typical of insulin binding data.
Research Organization:
Univ. of Colorado Health Sciences Center, Denver
OSTI ID:
6748738
Journal Information:
Endocrinology; (United States), Journal Name: Endocrinology; (United States) Vol. 113:6; ISSN ENDOA
Country of Publication:
United States
Language:
English

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Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AFFINITY
ANIMAL CELLS
ANTIBODIES
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CELL CULTURES
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
HORMONES
INSULIN
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LABELLING
LEUKOCYTES
LYMPHOCYTES
MATERIALS
NUCLEI
ODD-EVEN NUCLEI
PEPTIDE HORMONES
RADIOISOTOPES
REACTION KINETICS
RECEPTORS
SOMATIC CELLS
TRACER TECHNIQUES