SEQUENCE OF THE CDNA-ENCODING THE CA2+-ACTIVATED PHOTOPROTEIN OBELIN FROM THE HYDROID POLYP OBELIA-LONGISSIMA

A cDNA clone encoding the Ca2+-activated photoprotein, obelin (Obl), from Obelia longissima was sequenced. The nucleotide (nt) sequence contained two long overlapping open reading frames (ORFs), one of which encoded apoobelin (apoObl). The deduced amino acid (aa) sequence of apoObl revealed that this 195-aa protein has three EF-hand structures that are characteristic for Ca2+-binding domains. Strong aa homology was shown among apoObl, apoaequorin and apoclytin. The second ORF present in the obl cDNA consists of 139 codons and encodes a very basic protein with a calculated pI of 10.56 and a molecular mass of 16153 Da.