If only the partial sequence of the gene is available in the data base, then you may design gene specific primers from it and do RACE PCR. However, if the gene sequence has been published somewhere, you may contact the authors of the publication.
I totally agree with Shoib's suggestion. However, it is not clear, whether you tried everything to search data bases. Did you BLAST your sequence against non-redundant or species specific genomic data bases? Did you try