Selective diffusion barriers separate membrane compartments.
We have investigated exchange of molecules between different membrane domains on a highly compartmentalized cell, the spermatozoon. Using Alexa Fluor 555-cholera toxin B-subunit we have observed clustering of preexisting GM1 gangliosides which diffused across the anterior acrosome-equatorial segment interface but did not access the postacrosome. By contrast, single lipid and protein molecules readily exchanged between all three domains, although they diffused more slowly on nearing and crossing to the postacrosome. Thus, two types of diffusion interfaces are present on sperm heads, an "open" interface and a "mass filter" interface. The latter seems to be due to a protein-cytoskeleton network.
Bruckbauer
Andreas
A
Department of Chemistry, University of Cambridge, Cambridge, United Kingdom.
Dunne
Paul D
PD
James
Peter
P
Howes
Elizabeth
E
Zhou
Dejian
D
Jones
Roy
R
Klenerman
David
D
D000818:Animals; D002772:Cholera Toxin / Q000378:metabolism; D004058:Diffusion; D007700:Kinetics; D008297:Male; D021962:Membrane Microdomains / Q000378:metabolism*; D013094:Spermatozoa / Q000166:cytology* / Q000378:metabolism; D013552:Swine
D002772:Cholera Toxin