The current status of structural studies on proteins of the myelin sheath (review)

Myelin, the multilayered membrane structure surrounding axons, provides a u nique environment to its proteins, which are either transmembrane proteins or interacting intimately with the membrane surface. Although myelin-specif ic proteins have been studied for decades, remarkably little is known of th eir three-dimensional structures. In addition, the exact functions of myeli n proteins are to a large extent unknown. In this report, our current knowl edge of peripheral nervous system myelin protein structures is reviewed, an d the current status of attempts to solve the structures of full-length mye lin proteins is evaluated. Furthermore, molecular models for the extracellu lar domain of the myelin-associated glycoprotein and the putative kinase-li ke domain of 2',3'-cyclic nucleotide T-phosphodiesterase are presented and discussed.