G-protein α-subunits in cytosolic and membranous fractions of human neutrophils

U. Rudolph, D. Koesling, K. D. Hinsch, R. Seifert, M. Bigalke, G. Schultz, W. Rosenthal

Research output: Contribution to journalArticlepeer-review

Abstract

In plasma membranes of human neutrophils, we identified two major pertussis toxin substrates of 40 kDa Mr with pI values of 5.30 and 5.37. Only the acidic of the two substrates was also present in neutrophil cytosol. Two-dimensional tryptic peptide maps revealed a high degree of homology of cytosolic and particulate substrates. Purified G-protein βγ-complex stimulated pertussis toxin-catalyzed [32P]ADP-ribosylation of membranous and cytosolic substrates of neutrophils less than 2-fold and 6-fold, respectively. Hydrodynamic properties of the cytosolic substrate strongly suggested that it exists as a monomer. Purified G-protein βγ-complex increased the s20,ω value of the cytosolic substrate from 3.3 S to 4.0 S. The GTP analogue, guanosine 5′-O-(3-thiotriphosphate), promoted the release of pertussis toxin substrates from plasma membranes. An antiserum raised against a sequence specific for the Gi2 α-subunit reacted with 39-40 kDa proteins in plasma membranes and with an apparently single 40 kDa protein in cytosol. We conclude that neutrophil cytosol contains monomeric Gi2 α-subunits which - by interacting with hydrophobic βγ-complexes - may reversibly bind to the plasma membrane.

Original languageEnglish (US)
Pages (from-to)143-153
Number of pages11
JournalMolecular and Cellular Endocrinology
Volume63
Issue number1-2
DOIs
StatePublished - May 1989
Externally publishedYes

Keywords

  • Cytosol
  • G-protein
  • Neutrophil
  • Pertussis toxin
  • Plasma membrane
  • human

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Endocrinology

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