title: An analysis of the macronuclear actin genes of Oxytricha.
abstract: We have cloned and sequenced a 1.6-kb macronuclear molecule encoding actin from the hypotrichous ciliate Oxytricha nova. High-stringency Southern hybridization to native and digested macronuclear DNA shows that there is only one 1.6-kb actin-encoding molecule in O. nova. The 227-nucleotide 5' leader sequence contains AT-rich stretches punctuated by short GC regions. The AT-rich regions contain TATA-like sequences. However, other known eukaryote transcription regulatory sequences were not found. The 249-nucleotide 3' trailer sequence is also AT-rich and does not contain any obvious known eukaryotic mRNA processing signals. Sequence comparison with a closely related species, O. fallax, shows an 87% sequence similarity in the coding regions and an almost total lack of similarity in the noncoding regions of the molecules. However, a few small sequence similarities and motifs appear in the noncoding regions of the actin-encoding molecules of these two species. The actin-encoding molecule of O. nova could encode a polypeptide 374 amino acids long, the same size as some vertebrate cytoplasmic actins. Contrary to a previous report, we show that the actin-encoding molecule of O. fallax also codes for a polypeptide 374 amino acids long.
mesh_terms: D000199:Actins / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016798:Ciliophora / Q000235:genetics* / Q000378:metabolism; D004247:DNA / Q000032:analysis*; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization
chemical_list: D000199:Actins; D004247:DNA