Figure 1.

Deduced amino acid sequence alignment of the NR PCR products corresponding to 6 of the 13 studied groups. The sequences are compared with their mammalian or arthropod homologues, which are shaded. Only amino acids different to those in the first sequence are indicated. For each PCR product the number of sequenced clones is indicated. Gaps in the sequence alignment are indicated by stars. Interestingly, in Anemonia and Schistosoma we found several PCR products assigned to a given NR group (e.g., Schistosoma COUP and COUP II). In these cases the Roman number in parentheses is an arbitrary number needed to discriminate different gene versions. This suggests that, at least in these organisms, there is more diversity in NR than previously expected. The precise position of these extra copies was not determined, and it is not known whether these are secondary duplications specific to a given species or rather new receptor genes. In all cases these duplications are independent of the vertebrate gene duplication discussed in Fig. 3. GenBank codes of the sequences are U93406 to U93489.