APX (EC, 1.11.1.11) has a key role in scavenging ROS and in protecting cells against their toxic effects in algae and higher plants. A cDNA
encoding a peroxisomal ascorbate peroxidase, Am-pAPX1, was isolated from salt stressed leaves of Avicennia marina (Forsk.) Vierh. by EST
library screening and its expression in the context of various environmental stresses was investigated. Am-pAPX1 contains an ORF of 286 amino
acids coding for a 31.4 kDa protein. The C-terminal region of the Am-pAPX1 ORF has a putative transmembrane domain and a peroxisomal
targeting signal (RKKMK), suggesting peroxisomal localization. The peroxisomal localization of Am-pAPX1 was confirmed by stable transformation
of the GFP-(Ala)10-Am-pAPX1 fusion in tobacco. RNA blot analysis revealed that Am-pAPX1 is expressed in response to salinity (NaCl)
and oxidative stress (high intensity light, hydrogen peroxide application and excess iron). The isolated genomic clone of Am-pAPX1 was found to
contain nine exons. A fragment of 1616 bp corresponding to the 50 upstream region of Am-pAPX1 was isolated by TAIL-PCR. In silico analysis
of this sequence reveals the presence of putative light and abiotic stress regulatory elements.

http://www.sciencedirect.com/science/article/pii/S0981942808000867