Whale Hageman factor (factor XII): prevented production due to pseudogene conversion.
In Southern blot analysis of the Hind III-digested whale genomic DNA obtained from the livers of two individual whales, we detected a single band with a size of five kilobase pairs which hybridized to full length guinea pig Hageman factor cDNA. We amplified two successive segments of the whale Hageman factor gene by polymerase chain reaction (PCR), and sequenced the PCR products with a combined total of 1367 base pairs. Although all of the exon-intron assemblies predicted were identical to those of the human Hageman factor gene, there were two nonsense mutations making stop codons and a single nucleotide insertion causing a reading frame shift. We could not detect any message of the Hageman factor gene expression by northern blot analysis or by reverse transcription-polymerase chain reaction (RT-PCR) analysis. These results suggest that in the whale, production of the Hageman factor protein is prevented due to conversion of its gene to a pseudogene. The deduced amino acid sequence of whale Hageman factor showed the highest homology with the bovine molecule among the land mammals analyzed so far.
Department of Clinical Laboratory Medicine, School of Medicine, Kumamoto University, Honjo, Japan.
U
U
Semba
Y
Y
Shibuya
H
H
Okabe
T
T
Yamamoto
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D005174:Factor XII / Q000096:biosynthesis / Q000235:genetics*; D005786:Gene Expression Regulation / Q000502:physiology; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000379:methods; D011544:Pseudogenes; D014158:Transcription, Genetic; D014907:Whales / Q000235:genetics* / Q000378:metabolism
D005174:Factor XII