Cloning and Characterization of and Genes from the Non-Parasitic Japanese Lamprey .

Two cytochrome P450 genes homologous to human and were cloned from the non-parasitic Japanese lamprey . Lamprey mRNA had varied expression levels among individuals: about four orders of magnitude differences in larval liver and nearly three orders of magnitude differences in male adult liver. Overexpressed Cyp7a1 protein tagged with green fluorescent protein (GFP) was localized to the endoplasmic reticulum. Lamprey mRNA had relatively constant expression levels: within two orders of magnitude differences in larvae and adult liver and intestine. GFP-tagged Cyp27a1 protein was localized to mitochondria. The expression profiles of lamprey and genes and the cellular localizations of their products were in good agreement with their counterparts in mammals, where these two P450s catalyze initial hydroxylation reactions of cholesterol in classical and alternative pathways of bile acid synthesis, respectively. The mRNA levels in adult male liver showed significant negative correlations to both body weight and total length of the animal, implying the involvement of the gene in the production of female-attractive pheromones in sexually matured male livers. The lamprey Cyp7a1 contains a long extension of 116 amino acids between helices D and E of the protein. Possible roles of this extension in regulating the enzymatic activity of lamprey Cyp7a1 are discussed.