Purification and Characterization of a Novel Chemorepellent Receptor from Tetrahymena thermophila |
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Authors: | HG Kuruvilla TM Hennessey |
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Institution: | (1) State University of New York at Buffalo, Department of Biological Sciences, Hochstetter 610, Buffalo, New York 14260, USA, US |
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Abstract: | Chemosensory transduction and adaptation are important aspects of signal transduction mechanisms in many cell types, ranging
from prokaryotes to differentiated tissues such as neurons. The eukaryotic ciliated protozoan, Tetrahymena thermophila, is capable of responding to both chemoattractants (O'Neill et al., 1985; Leick, 1992; Kohidai, Karsa & Csaba, 1994, 1995)
and chemorepellents (Francis & Hennessey, 1995; Kuruvilla, Kim & Hennessey, 1997). An example of a nontoxic, depolarizing
chemorepellent in Tetrahymena is extracellular lysozyme (Francis & Hennessey, 1995; Hennessey, Kim & Satir, 1995). Lysozyme is an effective chemorepellent
at micromolar concentrations, binds to a single class of externally facing membrane receptors and prolonged exposure (10 min)
produces specific chemosensory adaptation (Kuruvilla et al., 1997). We now show that this lysozyme response is initiated by
a depolarizing chemoreceptor potential in Tetrahymena and we have purified the membrane lysozyme receptor by affinity chromatography of solubilized Tetrahymena membrane proteins. The solubilized, purified protein is 42 kD and it exhibits saturable, high affinity lysozyme binding.
Polyclonal antibodies raised against this 42 kD receptor block the in vivo lysozyme chemoresponse. This is not only the first
time that a chemoreceptor potential has been recorded from Tetrahymena but also the first time that a chemorepellent receptor has been purified from any unicellular eukaryote.
Received: 28 July 1997/Revised: 14 November 1997 |
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Keywords: | : Chemorepellent receptor — Signal transduction — Electrophysiology — Affinity Chromatography — Polyclonal antibodies — Chemosensory adaptation — Lysozyme |
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