CLONING AND SEQUENCE-ANALYSIS OF THE ALPHA-SUBUNIT OF THE CAT FLEA SODIUM-PUMP

We have cloned a cDNA that encodes the sodium pump alpha-subunit of th e cat flea Ctenocephalides felis. The deduced amino acid sequence of 1 037 residues is 90% homologous with the Drosophila alpha-subunit seque nce and shows 75% similarity to the sheep kidney alpha-subunit. One ch aracteristic unique to the insect polypeptides is an extended sequence at the N-terminus. Northern blot analysis of C. felis RNA detects two alpha-subunit transcripts with lengths of 3.8 and 4.4 kb. Sodium pump alpha-subunit sequences were readily detected in homogenates of flea midguts and in cDNA synthesized from midgut RNA.