Eukaryotic GUG translation start site?

[Zeev Pancer]

Hi, 
We have cloned a sponge (porifera) Tyrosine Kinase, and the ORF appears 
to begin with GTG instead of the common eukaryotic start site ATG. Can 
anyone refer me to literature or a databank entery of a protein with 
such a start site?
Thanks in advance,
Zeev Pancer, Ph.D.
Dept. of Applied Molecular Biology
Inst. fur Physiologische Chemie, Johannes Gutenberg-Universitat Mainz
E-mail: pancer at mzdmza.zdv.uni-mainz.de