Regionalization of transmembrane glycoproteins in the plasma membrane of boar sperm head is revealed by fracture-label.
Open Access
- 1 November 1983
- journal article
- research article
- Published by Rockefeller University Press in The Journal of cell biology
- Vol. 97 (5) , 1356-1364
- https://doi.org/10.1083/jcb.97.5.1356
Abstract
We used fracture-label and surface labeling techniques to characterize the distribution and topology of wheat germ agglutinin (WGA) receptors in the plasma membrane of boar sperm heads. We show that freeze-fracture results in preferential, but not exclusive, partition of WGA-binding sites with the outer (exoplasmic) half of the plasma membrane. Labeling of the inner (protoplasmic) half of the membrane is significant, and is denser over the areas that overlie the acrosome. Exoplasmic membrane halves are uniformly labeled. Analysis of freeze-fracture replicas revealed that the distribution of intramembrane particles over protoplasmic faces parallels that of WGA-binding sites as observed by fracture-label. Coating of intact spermatozoa with cationized ferritin results in drastic reduction of the labeling of both protoplasmic and exoplasmic membrane halves. Labeling of sperm cells lysed by short hypotonic shock fails to reveal the presence of WGA-binding sites at the inner surface of the plasma membrane. We conclude that: (a) all WGA-binding glycoconjugates are exposed at the outer surface of the membrane; (b) some of these glycoconjugates correspond to transmembrane glycoproteins that, on fracture, partition with the inner half of the membrane; (c) these transmembrane proteins are accumulated in the region of the plasma membrane that overlies the acrosome; and (d) parallel distribution of intramembrane particles and WGA-binding glycoproteins provides renewed support for the view of particles as the morphological counterpart of integral membrane proteins.This publication has 50 references indexed in Scilit:
- FINE STRUCTURE OBSERVATIONS ON THE DISTRIBUTION OF ANTIGENIC SITES ON GUINEA PIG SPERMATOZOAThe Journal of cell biology, 1974
- Topographical Location of H—Y Antigen on Mouse Spermatozoa by ImmunoelectronmicroscopyProceedings of the National Academy of Sciences, 1973
- Histoimmunochemical localization of three guinea-pig spermatozoal autoantigens.1973
- The distribution of negative surface charges on mammalian spermatozoaJournal of Anatomy, 1972
- The purification and characterization of wheat-germ agglutininBiochemical Journal, 1972
- THE STRUCTURE OF ERYTHROCYTE MEMBRANES STUDIED BY FREEZE-ETCHINGThe Journal of Experimental Medicine, 1972
- Molecular Probes of Spermatozoan StructuresProceedings of the National Academy of Sciences, 1971
- Freeze-etching studies of membrane structurePhilosophical Transactions of the Royal Society of London. B, Biological Sciences, 1971
- A freeze-etching study of rabbit spermatozoa with particular reference to head structuresJournal of Ultrastructure Research, 1970
- MEMBRANE VESICULATION AS A FEATURE OF THE MAMMALIAN ACROSOME REACTIONThe Journal of cell biology, 1967