Specific guanine nucleotide binding by membranes from cucurbita pepo seedlings

M. Jacobs, M. P. Thelen, R. W. Famdale, M. C. Astle, P. H. Rubery

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Abstract

A microsomal membrane preparation from hypocotyls of dark-grown Cucurbita pepo L. (zucchini) seedlings contains specific high-affinity binding sites for the non-hydrolyzable GTP analog guanosine 5′-[γ-thio]triphosphate (GTP-γ-S). Both the binding affinity and the pattern of binding specificity for GTP and guanine nucleoside triphosphate analogs are shared with the more thoroughly characterized animal G-proteins that are known to be involved in signal transduction. The sensitivity of GTP-γ-S binding to Mg+2 ions and temperature was similar to that reported for rabbit liver G-protein, although the plant complex dissociated more readily. GTP-γ-S could be recovered unchanged from the binding complex. Proteins (Mr 33 and 50 kDa) present in zucchini membrane preparations were revealed by immunoblotting with antiserum specific for the a subunit of platelet Gs. These may be homologous to animal G-proteins.

Original languageEnglish (US)
Pages (from-to)1478-1484
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume155
Issue number3
DOIs
StatePublished - Sep 30 1988

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ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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