cDNA Cloning and sequence analysis of retinoid X receptor (RXR) isoforms of the prawn(Macrobrachium nipponense)

RT-PCR and RACE(Rapid Amplification of cDNA Ends) methods were used for the isolation of the RXR from the ovary of Macrobrachium nipponense.Five different RXR isforms were obtained,including the MnRXRL2 isoform(1698 bp) with the longest open reading frame encoding 337 amino acids.Through comparing of the five nucleotide sequences,it is found that there are four alternative splicing sites among the five variant sequences,one in the A/B domain resulting in three different kinds of sequences,one in the T box in the linker D domain causing 3 forms(VQEERQR/VQVGGIEEERQR/VQVGGIE) in T box,two in the ligand-binding domain one of themis in H2-H3 domain,leading to two different forms(MnRXRL/MnRXRS),the other one cause the break in D domain,E/F domain(MnRXRM) is deleted.The deduced amino acid sequences of the five isoforms were highly similar to that of the other crustacean.These data suggest that RXR is relatively conservative in the progress of evolution.