Abstract
Membrane-bound forms of β1-4 galactosyltransferase (GalTase) are distributed in trans Golgi cisternae and plasma membrane, while a soluble form of the enzyme also exists in extracellular fluid. In epididymis, the soluble form has been found in luminal fluid and suggested to play a role on sperm maturation. In the present paper, regional distributions of the membrane-bound and soluble forms of GalTase were studied in rat epididymis. Immunohistochemical studies showed that a very high concentration of GalTase was localized in Golgi apparatuses of epididymal duct epithelium from initial segment to intermediate caput, although much lower amounts of GalTase were in efferent ducts, distal caput, corpus, and cauda. The same distribution pattern was also shown by biochemical assays of the microsomal GalTase activity. On the other hand, assays of the soluble GalTase activity in epididymal fluids revealed a relatively uniform distribution pattern. Even in initial segment and caput epididymis, only low levels of the activity were detected in the fluid.
