Fig. 1. Structure of sea urchin Delta homologues. (A) Schematic of LvDelta protein. SP, signal peptide; DSL, Delta/Serrate/LAG-2 domain; EGF, EGF repeats; TM, transmembrane domain; ICD, intracellular domain. (B) Nucleotide sequence of the LvDelta and SpDelta clones. Translational start and stop codons are boxed. Motifs common to Delta homologues are indicated. The site of the G-to-T mutation used to generate a premature stop codon and a truncated form of LvDelta is labeled with an arrowhead. The LvDelta clone continues to the poly(A) tail although the 3' untranslated region was not completely sequenced. The SpDelta clone terminates in the region encoding the intracellular domain. GenBank accession numbers for LvDelta and SpDelta are AY074791 and AY074792, respectively.