MOLECULAR EVOLUTION OF MYELIN PROTEOLIPID PROTEIN

We show that the major membrane protein of central nervous system myel in, proteolipid protein, evolved much more rapidly than it does now mo re than 300 million years ago. We reason that myelin proteolipid prote in evolved rapidly just after its appearance in vertebrates and that i ts evolutionary rate then gradually decreased. Comparison of the rates between the synonymous and nonsynonymous nucleotide substitutions for the cDNA suggests the possibility that positive selection operated on myelin proteolipid protein at least when it appeared invertebrates. ( C) 1997 Academic Press.