Molecular cloning of the cDNA for the major hemoglobin component from Paramecium caudatum

Nucleotide sequence of the cDNA for the major hemoglobin component of Paramecium caudatum was determined. An oligonucleotide was synthesized on the basis of the amino acid sequence, and the Paramecium cDNA library constructed in phage lambda gt11 was screened with it. Three positive clones, of which insert sizes were 0.4, 0.6, and 0.9 kbp, were obtained. Sequence analysis made clear that the 0.4-kbp cDNA retains a full length of the nucleotides encoding 116 amino acid residues, and that in the coding region it contains four TAA codons which are known to encode glutamine.