Major histocompatibility complex class I protein conformation altered by transmembrane potential changes.
The nature of charge distributions in membrane-bound macromolecular structures renders them susceptible to interaction with transmembrane potential fields. As a result, conformational changes in such species may be expected to occur when this potential is altered. We have detected reversible conformational change in the major histocompatibility complex (MHC) class I antigen in the plasma membrane of human JY cells, as monitored by flow-cytometric resonance energy-transfer, upon reduction of the transmembrane potential (depolarization). This change increased the intramolecular energy-transfer efficiency between fluorescent donor- and acceptor-labeled monoclonal antibodies directed, respectively, to epitopes on the light (beta 2-microglobulin) and the heavy chains of the MHC class I antigen. Repolarization of the depolarized samples restored the energy-transfer efficiency to the original values measured before depolarization. Depolarization caused similar relative changes in fluorescence resonance energy-transfer efficiency when Fab fragments were used for labeling MHC class I complex, suggesting that the observed phenomenon is not restricted to whole monoclonal antibodies.
Bene
L
L
Department of Biophysics, Medical University School, Debrecen, Hungary.
Szöllósi
J
J
Balázs
M
M
Mátyus
L
L
Gáspár
R
R
Ameloot
M
M
Dale
R E
RE
Damjanovich
S
S
D000911:Antibodies, Monoclonal / Q000276:immunology / Q000378:metabolism; D017951:Antigen Presentation / Q000276:immunology / Q000502:physiology; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000502:physiology; D002462:Cell Membrane / Q000502:physiology; D004735:Energy Transfer / Q000502:physiology; D004789:Enzyme Activation; D005434:Flow Cytometry / Q000379:methods; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D015395:Histocompatibility Antigens Class I / Q000737:chemistry* / Q000276:immunology / Q000502:physiology; D006801:Humans; D008564:Membrane Potentials; D018408:Patch-Clamp Techniques; D011487:Protein Conformation; D012235:Rhodamines; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013499:Surface Properties; D001613:beta 2-Microglobulin / Q000737:chemistry* / Q000276:immunology / Q000502:physiology
D000911:Antibodies, Monoclonal; D005456:Fluorescent Dyes; D015395:Histocompatibility Antigens Class I; D012235:Rhodamines; D001613:beta 2-Microglobulin; C009434:tetramethylrhodamine isothiocyanate; D000254:Sodium-Potassium-Exchanging ATPase; D016650:Fluorescein-5-isothiocyanate