The stringlike genes of the limpet Patella vulgata

As a first step in analyzing the function of a cdc25 homolog during the embryonic development of Patella vulgata (Pv), genomic clones encoding these stringlike proteins (Stl) were isolated and characterized. These clones belong to four groups which are derived from different regions of the Pv genome. As the sequences of Stl genes from two of these groups are almost identical, we suggest that these genes represent copies of the same gene. The Stl3 gene, which has been analyzed in detail, consists of four exons separated by three introns. Its sequence encodes a 250-amino-acid protein with a calculated weight of 28 kDa. The Stl protein contains regions conserved in all other cdc25 proteins. Stl messengers are not stored maternally in Pv oocytes and Stl transcription only starts after the first embryonic cleavages.