title: Possible interaction of haemoglobin with a low Mr GTP-binding protein, ram p25.
abstract: Haemoblobin (Hb) was observed to inhibit the GDP/GTP exchange activity of a low M(r) GTP-binding protein, ram p25. Hb also inhibited the [32P]GTP-hydrolysis activity of ram p25. These inhibitory effects of Hb were lost after incubation of Hb at 80 degrees C for 3 min, indicating that the ternary tetrameric structure of Hb is essential for the inhibitory effects on ram p25 activities. Hb did not inhibit [35S]GTP gamma S-binding of nucleotide-free ram p25. Methaemoglobin (MetHb) also inhibited both [3H]GDP-dissociation and [32P]GTP-hydrolysis activities of ram p25 in a very similar manner to Hb. The results strongly suggest that Hb may suppress physiological function(s) of ram p25 in vivo by inhibiting both [32P]GTP-hydrolysis and [3H]GDP-dissociation of ram p25.
authors.affiliation: Department of Molecular Pathobiochemistry, Gifu University School of Medicine, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nagata
authors.forename: Y
authors.initials: Y
authors.lastname: Okano
authors.forename: Y
authors.initials: Y
authors.lastname: Nozawa
mesh_terms: D000818:Animals; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006454:Hemoglobins / Q000737:chemistry / Q000494:pharmacology*; D006358:Hot Temperature; D006801:Humans; D006868:Hydrolysis; D046911:Macromolecular Substances; D008706:Methemoglobin / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins; D013329:Structure-Activity Relationship; D020691:rab GTP-Binding Proteins; D000075745:rab27 GTP-Binding Proteins
chemical_list: D006454:Hemoglobins; D046911:Macromolecular Substances; D012333:RNA, Messenger; D011994:Recombinant Proteins; D000075745:rab27 GTP-Binding Proteins; D006153:Guanosine Diphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D008706:Methemoglobin; D019204:GTP-Binding Proteins; C066694:RAB27A protein, human; C512961:Rab27a protein, rat; D020691:rab GTP-Binding Proteins