Abstract
Sphingomyelin (SM) is an abundant phospholipid in cell membranes. However, owing to the lack of appropriate probes, the subcellular distribution of SM remains unclear. In this study, we examined the localization of SM in COS-1 cells (green monkey kidney cells) by using two SM probes, lysenin and equinatoxin-II (EqtII). Both toxins stained SM in the plasma membrane (PM), and the stains were abolished by sphingomyelin synthase 2 (SMS2) knockdown or sphingomyelinase (SMase) treatment. Simultaneous labeling by the two toxins showed that the PM has heterogeneous SM pools: a SM pool stained by only lysenin, a SM pool stained only by EqtII, and a SM pool stained by both toxins. In permeabilized cells, lysenin exclusively stained late endosomes (LEs) among intracellular organelles, whereas EqtII stained recycling endosomes (REs) in addition to LEs. The intracellular SM stains by EqtII were abolished by sphingomyelin synthase 1 (SMS1) knockdown, but not by SMS2 knockdown. These results indicate that lysenin and EqtII label different SM pools and that SMS2 and SMS1 are responsible for the synthesis of SM in the PM and endomembranes, respectively, in COS-1 cells. The use of the two SM-binding probes may provide more insights into various sphingomyelin-mediated processes in different topological domains.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
