nhr-111 is a predicted gene (F44G3.9) that is a member of the superfamily of nuclear hormone receptors. Nuclear hormone receptors function by regulating the transcription of other downstream genes.
nhr-111 bears significant sequence homology to nuclear receptors that are involved in nervous system development in several species, such as
fax-1 of C. elegans, PNR and TLX of vertebrates, and tailless of Drosophila.
nhr-111 has a high degree of sequence homology to
fax-1 in the ligand-binding domain, but is more diverged from
fax-1 in the DNA-binding domain. Therefore,
nhr-111 may have been created by duplication of the
fax-1 locus, followed by divergence of DNA-binding domain sequences to create a new DNA-binding activity. Alternatively,
nhr-111 may have been created by a cassette-type mechanism in which the
fax-1 ligand-binding domain exons were duplicated and fused to DNA-binding domain exons descended from another nuclear receptor. The nearly-complete C. briggsae genomic sequence does not contain a gene that is closely related to
nhr-111, raising the interesting possibility that
nhr-111 is a nuclear receptor member that evolved after the relatively recent elegans-briggsae divergence. Another predicted gene, Y60A3A.15, bears close relationship to the
nhr-111 ligand-binding domain, but lacks a DNA-binding domain of any kind. This predicted gene also does not appear in the C. briggsae sequence.