The cytosolic G-protein alpha-subunit in human neutrophils responds to treatment with guanine nucleotides and magnesium.
The hydrodynamic properties of the Gi2 alpha-subunit in human neutrophil cytosol were analyzed. The S20,w value was 3.3 S at 30 degrees C and 4.1 S at 4 degrees C. Reconstitution of the cytosolic alpha-subunit with beta gamma-complex purified from porcine brain resulted in an S20,w value of 4.0 S at 30 degrees C and 4.2 S at 4 degrees C. Treatment of cytosol with G-protein-activating agents, GTP gamma S and MgCl2, decreased the S20,w value to 2.4 S at 30 degrees C and 2.9 S at 4 degrees C. Our results indicate that the cytosolic alpha-subunit of neutrophils is an inactive monomeric species at 30 degrees C capable of interacting with G-protein beta gamma-complex and responsive to treatment with activating agents leading to the two activated forms, alpha at 4 degrees C and alpha at 30 degrees C.
Rudolph
U
U
Institut für Pharmakologie, Freien Universität Berlin, Germany.
Schultz
G
G
Rosenthal
W
W
D000818:Animals; D001923:Brain Chemistry; D002499:Centrifugation, Density Gradient; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002850:Chromatography, Gel; D003600:Cytosol / Q000032:analysis*; D019204:GTP-Binding Proteins; D006150:Guanine Nucleotides / Q000494:pharmacology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D046911:Macromolecular Substances; D008274:Magnesium / Q000494:pharmacology*; D015636:Magnesium Chloride; D009504:Neutrophils / Q000032:analysis*; D011487:Protein Conformation; D015398:Signal Transduction; D013552:Swine; D013696:Temperature; D013873:Thionucleotides / Q000494:pharmacology
D006150:Guanine Nucleotides; D046911:Macromolecular Substances; D013873:Thionucleotides; D015636:Magnesium Chloride; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins; D008274:Magnesium