Possible involvement of superoxide anion in the induction of cyanide-resistant respiration in promoter in genes are differentially regulated in and expression in is usually mediated by the same element. by nitrate also occurs at the AOX protein and respiratory levels. A deletion analysis of the promoter region demonstrates that a short upstream segment (?253 to +59 with respect to the transcription start site) is sufficient AV412 to ensure gene expression and regulation, but that distal elements are required for full gene expression. The observed pattern of AOX regulation points to the possible conversation between chloroplast and mitochondria in relation to a potential increase of photogenerated ATP when nitrate is used as a nitrogen source. Besides the cyanide-sensitive cytochrome pathway, mitochondria from higher plants, some protists, and many fungi possess an alternative pathway that is resistant to cyanide but sensitive to salicylhydroxamic acid and and other Araceae, the free energy of the alternative pathway is involved in heat production during anthesis (Moore and Siedow, 1991). Although its precise function in other tissues is still not fully comprehended, the AOX is usually often considered to be a regulatory enzyme balancing carbon metabolism and electron transport. According to the energy overflow hypothesis (Lambers, 1982), shunting electrons to the alternative pathway would allow continued operation of glycolysis and tricarboxylic acid cycle when the cytochrome pathway is usually impaired or restricted by a high adenylate charge (for review, see Wagner and Krab, 1995; Vanlerberghe and McIntosh, 1997). The alternative pathway is also thought to prevent over-reduction of respiratory chain components that might otherwise result in the generation of harmful reactive oxygen species (for review, see Moller, 2001). Enhanced alternative respiration is usually observed following various developmental or environmental stimuli, and especially in stress conditions. Regulation of AOX activity is usually complex and occurs at both transcriptional and posttranslational levels. AV412 In isolated mitochondria from higher plants, AOX activity strongly increases upon reduction Mouse monoclonal to CD41.TBP8 reacts with a calcium-dependent complex of CD41/CD61 ( GPIIb/IIIa), 135/120 kDa, expressed on normal platelets and megakaryocytes. CD41 antigen acts as a receptor for fibrinogen, von Willebrand factor (vWf), fibrinectin and vitronectin and mediates platelet adhesion and aggregation. GM1CD41 completely inhibits ADP, epinephrine and collagen-induced platelet activation and partially inhibits restocetin and thrombin-induced platelet activation. It is useful in the morphological and physiological studies of platelets and megakaryocytes.
of an intersubunit disulphide bridge, yielding a non-covalently linked dimeric protein. Under its reduced form, the enzyme is usually activated by -keto acids, including pyruvate, through the formation of a thiohemiacetal. Both regulatory mechanisms occur at the same highly conserved Cys residue of the enzyme (for review, see Affourtit et al., AV412 2002). In fungi and protozoa, most studies so far point to a monomeric AOX that is only stimulated by ADP, AMP, and GMP, whereas the AOX from higher plants is usually unaffected by these purine nucleotides (for review, see Joseph-Horne et al., 2001). Comparisons of AOX protein sequences reveal a domain name of about 40 amino acids surrounding the regulatory Cys in the herb sequences that is not found in the fungal sequences (Umbach and Siedow, 2000). This conserved domain name may be involved in dimerization and posttranslational regulation of the herb enzyme. These discrepancies in structural and regulatory properties between AOXs from both groups suggest potential differences in their physiological functions (for review, see Joseph-Horne et al., 2001). In higher plants, where AOX is generally encoded by small multigene families, many conditions are known to enhance gene transcription and/or AOX protein accumulation. Some of these conditions include saline (Hilal et al., 1998) and oxidative stresses (Wagner, 1995; Vanlerberghe and McIntosh, 1996), exposure to heavy metals (Padua et al., 1999), inhibition of mitochondrial protein synthesis (Zhang et al., 1996), cytochrome pathway restriction (Vanlerberghe and McIntosh, 1992, 1994; Saisho et al., 1997; Wagner and Wagner, 1997; Tanudji et al., 1999; Ducos et al., 2001), and incubation with metabolites such as acetate, Cys, or salicylic and citric acids (Elthon et al., 1989; Rhoads and McIntosh, 1992; Vanlerberghe and McIntosh, 1996; Lennon et al., 1997; Potter et al., 2000). In fungi, AOX induction is especially dependent on cytochrome pathway restriction (Lambowitz et al., 1989; Sakajo et al., 1991; Minagawa et al., 1992; Li et al., 1996; Yukioka et al., 1998; Huh and Kang, 1999, AV412 2001) and triggering by reactive oxygen species (Yukioka et al., 1998; Huh and Kang, 2001). The alternative pathway of the unicellular green alga has been mainly investigated in terms of cell respiratory.