Rather, it appears that vertebrate proteins them- selves are more complex than those of invertebrates; that is, vertebrate proteins tend to have more domains (modules) than invertebrate proteins, and these modules are more often selectively expressed through alternative gene splic- ing (a phenomenon in which a given gene transcript can be processed in multiple ways so as to yield different proteins when translated; Section 26-3B). In fact, most vertebrate genes encode several different although similar proteins.