Journal article


G proteins and Ca2+-modulated protein kinases of a plasma membrane-enriched fraction and isolated eyespot apparatuses of Spermatozopsis similis (Chlorophyceae)


Publication Details
Author(s): Schlicher U, Linden L, Calenberg M, Kreimer G
Publisher: Taylor & Francis
Publication year: 1995
Volume: 30
Journal issue: 4
Pages range: 319-330
ISSN: 0967-0262

Abstract

Knowledge about possible elements involved in signal transduction and adaptational phenomena during phototaxis of flagellate green algae is limited. In order to identify such putative elements we present here: (i) the isolation and characterisation of an enriched plasma membrane fraction of Spermatozopsis similis, and (ii) a comparison of the distribution of Ca2+-dependent putative kinases and G proteins, as recognised by antibodies directed against mammalian G(alpha)-subunits, in the plasma membrane preparation and isolated eyespot apparatuses of this green alga. In western blot analyses a 54 kDa protein reacted with an antiserum against a conserved sequence of G protein alpha-subunits (anti-alpha common). A 43 kDa protein was recognised by a serum against the G(alpha)-subunit of transducin. These proteins were enriched in the eyespot fraction and to a lesser extent in the plasma membrane fraction. Two polyclonal antisera against C-terminal peptides of animal G(alpha)-subunits also labelled a 43 kDa and 54 kDa protein in the eyespot preparations. Additionally four putative Ca2+-dependent kinases or their catalytic subunits (47, 48, 77 and 82 kDa) were identified in the plasma membrane fraction by a gel kinase assay following electrophoretic separation. The 82 kDa protein was specifically enriched in the plasma membrane fraction, while the other putative kinases were also enriched in the eyespot fraction but not in other subcellular fractions. Monoclonal antibodies directed against a soybean Ca2+-dependent protein kinase cross-reacted with a 61 kDa protein in the plasma membrane and a 60 kDa protein in the soluble fraction. Only a very faint response was observed in the fraction enriched in eyespot apparatuses. Our results indicate (i) a low cross-contamination of the eyespot apparatus preparation by normal plasma membrane constituents and (ii) the regulatory potential for the identified kinases and G proteins in blue/green-light-dependent photoresponses of Spermatozopsis similis.



How to cite
APA: Schlicher, U., Linden, L., Calenberg, M., & Kreimer, G. (1995). G proteins and Ca2+-modulated protein kinases of a plasma membrane-enriched fraction and isolated eyespot apparatuses of Spermatozopsis similis (Chlorophyceae). European Journal of Phycology, 30(4), 319-330. https://dx.doi.org/10.1080/09670269500651111

MLA: Schlicher, Ulrike, et al. "G proteins and Ca2+-modulated protein kinases of a plasma membrane-enriched fraction and isolated eyespot apparatuses of Spermatozopsis similis (Chlorophyceae)." European Journal of Phycology 30.4 (1995): 319-330.

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