Evidence that L1AD3, an apoptosis-inducing cyclic peptide, binds a leukemic T-cell membrane protein receptor

Human leukemic T-lymphocytes undergo extensive and rapid apoptosis in the presence of L1AD3, a small cyclic peptide derivative of cobra cardiotoxin. The first step in this process involves its binding to membranes of susceptible cells. By the use of a biotin “handle” synthetically incorporated at th...

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Bibliographic Details
Published in:Archives of biochemistry and biophysics 2004-12, Vol.432 (1), p.88-101
Main Authors: Smith, Charles A., Hinman, Channing L.
Format: Article
Language:English
Subjects:
Animals
Apoptosis
Avidin - chemistry
B-Lymphocytes - metabolism
Binding
Binding Sites
Binding, Competitive
Biotin
Biotin - chemistry
Biotinylation
Cardiotoxin
Cell Membrane - metabolism
Cell Survival
Chromatography, High Pressure Liquid
Cobra Cardiotoxin Proteins - chemistry
Cobra Cardiotoxin Proteins - metabolism
Cross-Linking Reagents - pharmacology
Disulfides
Dose-Response Relationship, Drug
Electrophoresis, Polyacrylamide Gel
Flow Cytometry
Fluorescence Resonance Energy Transfer
FRET
Humans
L1AD3
Leukemia
Leukemia, T-Cell - metabolism
Lymphocyte
Macrophages - metabolism
Mass Spectrometry
Models, Chemical
Models, Molecular
Monocytes - metabolism
Oxygen - metabolism
Peptides - chemistry
Protein Binding
Protein Structure, Tertiary
Receptor
Scatchard
Spectrometry, Fluorescence
T-Lymphocytes - metabolism
Trypsin - pharmacology
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Summary:Human leukemic T-lymphocytes undergo extensive and rapid apoptosis in the presence of L1AD3, a small cyclic peptide derivative of cobra cardiotoxin. The first step in this process involves its binding to membranes of susceptible cells. By the use of a biotin “handle” synthetically incorporated at the N-terminus of L1AD3, we show that binding is saturable and selective: normal human peripheral blood lymphocytes do not bind this peptide. Fluorescence resonance energy transfer experiments indicate that the binding sites are separated by at least 55 Å. Loss of binding occurs if membrane proteins are enzymatically degraded, suggesting that L1AD3’s target is a cell-membrane surface protein receptor. Finally, crosslinking of cyclic BTNL1AD3 peptide to a leukemic T-cell membrane surface receptor, as examined using a biotin–avidin blot, indicated a molecular weight of approximately 34,400.
ISSN:0003-9861
1096-0384
DOI:10.1016/j.abb.2004.08.010