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Ziegler, I. ; Schwulera, U.

Modulation of interleukin 2 high-affinity binding by lymphocyte-derived tetrahydrobiopterin: Pterins as potential participants in the control of interleukin 2 receptor assembly.

J. Cell. Biochem. 41, 103-112 (1989)
DOI
Open Access Green as soon as Postprint is submitted to ZB.
In this report, we have examined whether (6R)-tetrahydrobiopterin (H4biopterin) modulates the binding of interleukin 2 to high-affinity sites of the cloned mouse cytotoxic T-lymphocyte clone CTLL-2. Scatchard plot analysis of the equilibrium binding data reveals increased affinity when the cells are exposed simultaneously to interleukin 2 and to the pterin. The K(d) values are statistically significantly reduced from 1.4 x 10-11M to 0.78 x 10-11M interleukin 2. The dissociation kinetics of the ligand were followed at 4°C after equilibrium binding under high-affinity conditions (1.2 x 10-10M interleukin 2). In the presence of H4 biopterin, the dissociation rate constant (k-1) decreases from 6.2 x 10-3 min-1 to 3.0 x 10-3 min-1 and the half-time for dissociation increases from 106.8 min to 218.0 min. As a third approach interleukin 2 was bound to the surface of cells under high-affinity conditions by incubation in the cold and the internalization kinetics upon warming were determined. Sigmoidal-shaped kinetics of endocytosis in control cells indicate that the internalization rates increase only gradually. The presence of H4 biopterin causes an apparent immediate transition from higher-order kinetics to a linear response so that maximum internalization rates are reached immediately upon warming. The data show that lymphocyte-derived H4 biopterin in vitro at concentrations ranging from 2-8 x 10-7M modulates interleukin 2 high-affinity binding and that H4 biopterin potentially participates in the control of interleukin 2 receptor assembly.
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Publication type Article: Journal article
Document type Scientific Article
Corresponding Author
Keywords High-affinity Receptor ; Interleukin 2 Binding
ISSN (print) / ISBN 0730-2312
e-ISSN 1097-4644
Journal Journal of Cellular Biochemistry
Quellenangaben Volume: 41, Issue: 2, Pages: 103-112 Article Number: , Supplement: ,
Publisher Wiley
Non-patent literature Publications
Reviewing status Peer reviewed