Structure and function of sulfoglycolipids in the kidney and testis

Galactosylsulfatide (SM4s), a sulfated glycosphingolipid (GSL), is present most abundantly in the brain as the major component of the myelin sheath. Next to the nervous tissue, the kidneys of mammals are rich in sulfated GSLs. Not only SM4s but also various sulfated GSLs, including lactosylsulfatide (SM3), bis-sulfated GSLs and a sulfated ganglioside, have been isolated and characterized from the kidney, suggesting their function as ion barriers to environmental osmolality. On the other hand, seminolipid (SM4g), a sulfated glyceroglycolipid (GGL), is the principal glycolipid in spermatozoa of mammals, suggesting that SM4g plays an essential role in spermatogenesis and the fertilization process. In this review, we summarize the results of the knockout mice generated by gene-targeted disruption of enzymes which catalyze synthesis of SM4s and SM4g, and discuss the potential function of sulfoglycolipids in the kidney and testis. As the basis of functional analyses, the progress of analytical methods of sulfoglycolipids is also described.