Binding of guanine nucleotides to bronchial membranes: effect of maturation.
Guanosine 5-[y-thio]triphosphate ([35S]GTP gamma S) binding to guinea pig bronchial membranes from immature and mature guinea pigs was rapid (Kon: 3.8 x 10(5) mol-1 min-1), saturable (Bmax: 160 pmoles/mg protein) and of high affinity (Kd: 0.6 microM). [35S]GTP gamma S rapidly dissociated in the absence of magnesium (Koff: 0.06 min-1), but 50 mM magnesium inhibited the dissociation. Maturation did not alter the affinity of the ligand, but Bmax (pmoles/mg DNA) was greater in preparations from mature animals (929 +/- 16 vs. 620 +/- 64). [35S]GTP gamma S was displaced by guanine nucleotides with a rank order of potency of GDP beta S = Gpp(NH)p > GDP > GTP, but not by ATP. We conclude that [35S]GTP gamma S is a specific and useful method to quantitate bronchial membrane-bound GTP-binding proteins. The technique shows that there is a significant increase in the cellular content of G-proteins during maturation.
John B. Pierce Laboratory, New Haven, Connecticut, USA.
F J
FJ
Roux
K J
KJ
Rhoden
J S
JS
Douglas
D000375:Aging / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D001980:Bronchi / Q000378:metabolism*; D004261:DNA Replication; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006168:Guinea Pigs; D008566:Membranes / Q000378:metabolism; D011485:Protein Binding; D015398:Signal Transduction
D016244:Guanosine 5'-O-(3-Thiotriphosphate); D019204:GTP-Binding Proteins