MAL (myelin and lymphocyte protein), also known as T lymphocyte maturation-associated protein, is a nonglycosylated hydrophobic integral membrane protein belonging to the MAL family of proteolipids. MAL is highly enriched in nervous system myelin and in rafts and apical membranes of epithelial cells. It is involved in forming, stabilizing and maintaining glycosphingolipid-enriched membrane microdomains. MAL maintains the myelin sheath and, by controlling the sorting and trafficking of oligodendrocytes, it is involved in central nervous system paranode maintenance. MAL is a component of lipid rafts in myelinating cells. Association with glycosphingolipids may result in protein-lipid microdomain formation in myelin. MAL has been localized to the endoplasmic reticulum of T cells and in compact myelin of cells in the nervous system. MAL is primarily expressed by oligodendrocytes and Schwann cells in the intermediate and late stages of T cell differentiation.