Author/Editor		Sedej, Simon; Rupnik, Marjan; Zorec, Robert
Title		Endocytosis-dominated membrane area decrease requires Rab5 protein in rat melanotrophs
Type		članek
Source		Ann NY Acad Sci
Vol. and No.		Letnik 1048
Publication year		2005
Volume		str. 272-80
Language		eng
Abstract		Eukaryotic cells internalize extracellular macromolecules by endocytosis and it was shown that RabS protein is required for this process. While it is clear that endocytosis consists of vesicle fission from the plasma membrane, the role of RabS protein in the plasma membrane surface area changes is still unclear. Here we studied whether RabS is required for membrane surface area changes in rat melanotrophs-cells deriving from the pituitary pars intermedia. The presence of this protein in melanotrophs was probed by immunocytochemistry and its putative role in membrane area dynamics was monitored electrophysiologically with membrane capacitance measurements as this parameter directly reflects changes in membrane surface area. We found that RabS protein exists in melanotrophs. At [Ca2+]i, < 3 uM, endocytosis-dominated membrane capacitance decrease was found to be blocked by microinjection of specific Rab5 antibody. At high [Ca2+]i, Rab5 antibody did not affect the steady-state increase in membrane capacitance, while it elevated the rate of membrane capacitance increase, which is consistent with an inhibition of endocytosis.
Descriptors		ENDOCYTOSIS GTP-BINDING PROTEINS PITUITARY GLAND MEMBRANE POTENTIALS ELECTRIC CONDUCTIVITY IMMUNOHISTOCHEMISTRY CELLS, CULTURED EXOCYTOSIS CALCIUM PATCH-CLAMP TECHNIQUES RATS, WISTAR