EVIDENCE FOR THE INVOLVEMENT OF GTP-BINDING PROTEINS IN THE PROCESS OF ANAEROBIC GAMMA-AMINOBUTYRATE ACCUMULATION IN RICE ROOTS

The pretreatment of rice roots for Ih in aerobic conditions with GTP g amma S or AlF4- induced a higher gamma-aminobutyrate (GABA) accumulati on during 3 h of anoxia, while GDP beta S or GDP slightly inhibited th is process. Pretreatment with the Ca2+-channel blocker ruthenium red ( RR) or the CaM-antagonist trifluoperazine inhibited the GTP gamma S- o r the AlF4--stimulated anaerobic GABA accumulation. At elevated RR con centrations, GABA accumulation was completely inhibited both in the ab sence and presence of AlF4-. Furthermore, western immunodetection with anti-a common antibody revealed a higher amount of G alpha-like prote ins (30 and 28 kDa) in the presence of GTP gamma S or AlF4-. These dat a are discussed in relation to an involvement of G proteins in the tra nsduction af an anaerobic signal.