Extensive maternal representation of DNA-binding proteins that interact with regulatory target sites of the Strongylocentrotus purpuratus CyIIIa gene.

Nine different embryonic transcription factors interact at specific target sites in the cis-regulatory domain of the Strongylocentrotus purpuratus CyIIIa gene. We tested eight of these site sequences and show here that for every one a DNA-binding protein was present in unfertilized egg cytoplasm. The concentrations of active DNA-binding proteins per egg were estimated. We also present a new and convenient method for preparation of a material cytoplasmic fraction that retains these factors in active form.