GTP binding activity of membrane proteins in isolated barley embryo is enhanced by abscisic acid

摘要

Pharmacological studies showed that an inhibitor (pertussis toxin) or activator (mastoparan) of the G alpha -subunit of heterotrimeric GTP binding proteins can counteract the effect of the plant hormone abscisic acid (ABA) in the inhibition of barley embryo germination. The presence of several GTP binding proteins (ranging from 15 to 48 kDa) in membrane fractions of barley embryos was demonstrated by specific [ alpha - superior 3 superior 2P]GTP labeling of proteins and by Western blotting using antibodies against highly conserved G protein alpha - subunit or Ras protein. GTP binding was enhanced in protein fractions from ABA-treated embryos, especially concerning poly-peptides of Mr 42, 29, 28, 27, and 25 kDa. Our data suggest that GTP-binding proteins are involved ABA- induced responses in barley embryo.