Spermatozoa from a marsupial, the brushtail possum, contain beta1,4-galactosyltransferase.
Beta1,4-galactosyltransferase-I (GalTase-I) is one of the key molecules on the sperm surface of eutherian mammals that is likely to be involved in binding to the egg coat, the zona pellucida, to mediate sperm-egg interaction. In laboratory mice, the species for which most data are available, this protein functions as a receptor for the zona pellucida protein ZP3 of the oocyte and, upon binding, triggers the sperm acrosome reaction. In the present study, we investigated the presence and abundance of GalTase-I in epididymal sperm extracts of a marsupial, the brushtail possum, Trichosurus vulpecula. For this, spermatozoa were collected from cauda epididymides and the amount of beta1,4-galactosyltransferase activity in washed sperm extracts was compared with that of porcine spermatozoa. Overall beta1,4-galactosyltransferase enzyme activity was found to be more abundant in possum sperm extracts than those from porcine spermatozoa (P<0.05). Immunoblots with an antibody to mouse GalTase-I revealed that the molecular weight of possum spermatozoa GalTase-I was 66 kDa, which is similar to the molecular weight of GalTase-I in spermatozoa from eutherian mammals. The molecular weight of GalTase-I was the same in sperm extracts collected from the caput and cauda epididymides. These results demonstrate that GalTase-I is indeed present in possum spermatozoa and thus it may be a gamete receptor molecule on the sperm surface of marsupials as well as those of eutherian mammals.
Braundmeier
A G
AG
Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Breed
William G
WG
Miller
D J
DJ
D000818:Animals; D015153:Blotting, Western; D008297:Male; D009237:N-Acetyllactosamine Synthase / Q000032:analysis*; D013094:Spermatozoa / Q000737:chemistry / Q000201:enzymology*; D048330:Trichosurus / Q000502:physiology*
D009237:N-Acetyllactosamine Synthase