Cloning and tissue distribution of two Na+/H+ exchanges from the Malpighian tubules of Aedes aegypti
2002
Hart, S.J. | Knezetic, J.A. | Petzel, D.H.
A Na+/H+ exchanger (NHE) on the apical membrane of mosquito Malpighian tubule (MT) cells is believed to participate in the blood-feeding mosquitos vital secretion of Na+ and fluid. This study presents the molecular cloning, primary structure, and tissue distribution of two cDNAs encoding Aedes aegypti mosquito MT NHEs. The cDNA sequences were obtained from mosquito MT total RNA using reverse transcription-polymerase chain reaction (RT-PCR) and 5' and 3' rapid amplification of cDNA ends (RACE). The two sequences encode proteins of 678 and 1,179 amino acids with calculated molecular weights of 74,473 and 130,276, respectively. When comparing the 678 amino acid protein to the first 678 amino acids of the other protein, the two clones show 98% identity to each other. They also exhibit high identity to Drosophila melanogaster NHEs. Hydropathy analysis reveals that while both clones have 10-13 transmembrane segments, the 1,179 amino acid protein has an extensive carboxy terminus while the 678 amino acid protein has an extremely short carboxy terminus. RT-PCR analysis shows that both clones are expressed in the mosquito Malpighian tubules at the larval and pupal stages, in addition to the adult stage before and after blood-feeding. Expression of both clones was also detected in adult mosquito ovaries, midguts, and hindguts.
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