Gene cloning of a monomeric hemoglobin of a widely distributed chironomid Polypedilum nubifer |
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Authors: | Kawai Koichiro Muraguchi Atsushi |
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Institution: | (1) Laboratory of Ecology, Faculty of Applied Biological Science, Hiroshima University, Kagamiyama, Higashihiroshima-shi, Hiroshima 739, Japan;(2) Department of Immunology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Sugitani, Toyama-shi, Toyama 930-01, Japan |
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Abstract: | A gene of a monomeric hemoglobin, the Pol n component of MV, of a chironomid species, Polypedilum nubifer, was cloned by screening
the larval cDNA library with a nucleotide probe corresponding to the N-terminal sequence of purified MV. A clone, 8N, was
755 bp long and comprised a 60 bp 5′ non-coding region, a 209 bp 3′ non-coding region and a 486 bp coding region for 160 amino
acids. A comparison of N-terminal sequence of purified MV with that estimated from the DNA sequence of clone 8N, revealed
the existence of a signal peptide consisting of 14 residues. This signal peptide was almost exclusively composed of hydrophobic
amino acids, suggesting the peptide functions in preglobin transport across the endoplasmic reticulum. The estimated sequence
of mature globin of MV showed only 41% of homology to that of CTT-IV, a chromatographically similar monomeric Hb to MV, of
an another chironomid species, Chironomus thummi thummi, in a 146 alignment. However, displacements in hydrophilic ⇆hydrophobic
manner were observed only at 28 positions whereas those in hydrophobic ⇆hydrophobic or hydrophilic ⇆hydrophilic manner were
observed at 45 positions. Furthermore, a comparison of the haem contact positions between these two Hbs showed a remarkable
conservance and displacements only in hydrophilic ⇆ hydrophilic or hydrophobic ⇆hydrophobic manner, suggesting the crucial
role of these positions in Hb functionality.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | chironomid Polypedilum nubifer monomeric hemoglobin gene cloning |
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