Characterization of a cDNA encoding a homolog of actin-related protein 4 from a marine red alga Porphyra yezoensis

ABSTRACT:   A cDNA ( PyARP4 ) containing an open reading frame for a protein of 573 amino acids was identified in the marine red alga Porphyra yezoensis . The conceptual PyARP4 protein exhibits significant similarity to actin-related protein (ARP) 4 in the terrestrial plant Arabidopsis . Comparison of the deduced amino acid sequence showed moderate sequence identity (30%) to a conventional actin in P. yezoensis , as seen in comparisons between ARP and conventional actins of other organisms. A putative bipartite nuclear localization signal and an actin motif were found within the PyARP4 amino acid sequence. In a phylogenetic analysis, the PyARP4 was found to cluster with the ARP4 of other organisms. The expression level of PyARP4 did not change significantly among four developmental stages of life cycle and was lower than that of a conventional actin. This cDNA therefore may serve as a useful internal standard in gene expression analyses of differentially expressed genes in P. yezoensis .