Figure 4. Evidence that a Ryk receptor tyrosine kinase gene is present Branchiostoma floridae.

Ryk receptor tyrosine kinases, consisting of WIF domain (WIF) and a tyrosine kinase domain (Pkinase_Tyr) are present in all groups of Bilateria as well as in Cnidaria. Although the B. belcheri genome was predicted to encode a full-length Ryk receptor tyrosine kinase (247370_PRF0), no orthologue with the same domain architecture was found in the predicted proteome of B. floridae¹⁴. Our analysis of the B. floridae genome provided evidence for a Ryk gene (RYK_Bfloridae) that encodes a protein with the same domain organization as that of B. belcheri (a). Note that the predicted Ryk receptor tyrosine kinases of B. belcheri and B. floridae are 95% identical at the amino acid sequence level. In the alignment of the two sequences the residues supported by ESTs (BW781727.1, BW727057.1 and BW727057) are underlined (b).