Patch-clamp capacitance measurements: new insights into the endocytic uptake of transferrin.
Since its introduction by Neher and Sakmann in 1976 the patch-clamp technique has been extensively used to study processes such as signalling and synaptic transmission, but also for monitoring endo- and exocytosis. Since biological membranes behave like electrical capacitors high-resolution measurements of membrane capacitance allow detection of small changes in membrane surface area that accompany exocytosis and endocytosis. We here describe our recent work on patch-clamp capacitance measurements in stably transfected HeLa cells expressing HFE, the hereditary hemochromatosis gene product, under the control of a tetracycline-sensitive promotor. By means of whole-cell and cell-attached techniques we were able to reveal transferrin-induced decreases in membrane capacitance reflecting increased endocytosis at the single cell level. Moreover, cell-attached recordings revealed significant alterations in the formation of single endocytic vesicles. Time-resolved measurements of cell membrane capacitance provide a new methodological approach to study the endocytic uptake of transferrin and its regulation by HFE, the hereditary hemochromatosis protein.
Schwake
Lukas
L
Department of Internal Medicine (Gastroenterology), Faculty of Medicine, University of Heidelberg, Bergheimer-Strasse 58, D-69115 Heidelberg, Germany. Lukas_Schwake@gmx.net
Henkel
Andreas W
AW
Riedel
Hans D
HD
Stremmel
Wolfgang
W
D022162:Cytoplasmic Vesicles / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology*; D006367:HeLa Cells; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I / Q000378:metabolism; D006801:Humans; D007501:Iron / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D018408:Patch-Clamp Techniques / Q000379:methods; D014168:Transferrin / Q000378:metabolism*
C103673:HFE protein, human; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; D014168:Transferrin; D007501:Iron