Is there really only one protein resembling Factors V and VIII in the lamprey genome?
As noted above, if there is more than one protein resembling Factors V and VIII, then Doolittle and Miller’s argument that the lamprey lacks one of those two proteins disintegrates. So let’s now return to this important question: Does Doolittle’s data support his claim that there is only one possible gene in the lamprey database resembling Factors V or VIII, and thus at most only one of the two proteins exists in the lamprey? I don’t think it does at all. Why not? Factors V and VIII are extremely similar, and Doolittle’s paper admits that both factors yielded dozens of hits in the lamprey genome database. The proteins have a highly similar domain and sequence structure. Both Factors V and VIII are composed of 3 types of components: three “A” domains (that are nearly identical), a “B” domain, and then a “discoidin” domain at the C-terminus. In both factors V and VIII, the A domains and “discoidin” domain are extremely similar, and the only major differences between the two factors lie i
