REGIONAL DISTRIBUTION OF BETA-1-4 GALACTOSYLTRANSFERASE IN RAT EPIDIDYMIS

Membrane-bound forms of beta 1-4 galactosyltransferase (GalTase) are d istributed in trans Golgi cisternae and plasma membrane, while a solub le form of the enzyme also exists in extracellular fluid. In epididymi s, the soluble form has been found in luminal fluid and suggested to p lay a role on sperm maturation. In the present paper. regional distrib utions of the membrane-bound and soluble forms of GalTase were studied in rat epididymis. Immunohistochemical studies showed that a very hig h concentration of GalTase was localized in Golgi apparatuses of epidi dymal duct epithelium from initial segment to intermediate caput. alth ough much lower amounts of GalTase were in efferent ducts, distal capu t, corpus. and cauda. The same distribution pattern was also shown by biochemical assays of the microsomal GalTase activity. On the other ha nd, assays of the soluble GalTase activity in epididymal fluids reveal ed a relatively uniform distribution pattern. Even in initial segment and caput epididymis, only low levels of the activity were detected in the fluid.