<P> Fusion proteins or chimeric (\ kī - ˈmir - ik) proteins (literally, made of parts from different sources) are proteins created through the joining of two or more genes that originally coded for separate proteins . Translation of this fusion gene results in a single or multiple polypeptides with functional properties derived from each of the original proteins . Recombinant fusion proteins are created artificially by recombinant DNA technology for use in biological research or therapeutics . Chimeric or chimera usually designate hybrid proteins made of polypeptides having different functions or physico - chemical patterns . Chimeric mutant proteins occur naturally when a complex mutation, such as a chromosomal translocation, tandem duplication, or retrotransposition creates a novel coding sequence containing parts of the coding sequences from two different genes . Naturally occurring fusion proteins are commonly found in cancer cells, where they may function as oncoproteins . The bcr - abl fusion protein is a well - known example of an oncogenic fusion protein, and is considered to be the primary oncogenic driver of chronic myelogenous leukemia . </P> <P> Some fusion proteins combine whole peptides and therefore contain all functional domains of the original proteins . However, other fusion proteins, especially those that occur naturally, combine only portions of coding sequences and therefore do not maintain the original functions of the parental genes that formed them . </P>

What type of mutation produces the bcr-abl chimeric protein