The hemoglobin gene of the deep-sea clam Calyptogena soyoae has a novel intron in A-helix.
The cDNAs encoding two dimeric hemoglobins, Hbs I and II, of the deep-sea clam Calyptogena soyoae were amplified by PCR and the complete nucleotide sequences determined. The cDNA-derived amino acid sequences agreed completely with those determined chemically. Many of the molluscan intracellular globin genes have a characteristic four-exon/three-intron structure, with the precoding and two conventional introns conserved widely in animal globin genes. In this work we have determined the exon/intron organization of two hemoglobin genes of the deep-sea clam C. soyoae. Surprisingly, this gene has no precoding intron but instead contains an additional intron in the A-helix (A3.1), together with the two conventional introns (B12.2 and G6.3). This observation suggests that the precoding intron has been lost and the insertion of intron in A-helix occurred in the genes of Calyptogena. Alternatively, the sliding of intron from precoding to A-helix might have occurred.
Suzuki
T
T
Laboratory of Biochemistry, Faculty of Science, Kochi University, Kochi 780-8520, Japan. suzuki@sc.kochi-u.ac.jp
Ohta
S
S
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D049872:Bivalvia / Q000737:chemistry / Q000235:genetics*; D018076:DNA, Complementary; D019281:Dimerization; D019143:Evolution, Molecular; D005091:Exons; D006454:Hemoglobins / Q000737:chemistry / Q000235:genetics*; D007438:Introns; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017433:Protein Structure, Secondary
D018076:DNA, Complementary; D006454:Hemoglobins