Imaging the selective binding of synapsin to anionic membrane domains.
Synapsins are membrane-associated proteins that cover the surface of synaptic vesicles and are responsible for maintaining a pool of neurotransmitter-loaded vesicles for use during neuronal activity. We have used atomic force microscopy (AFM) to study the interaction of synapsin I with negatively charged lipid domains in phase-separated supported lipid bilayers prepared from mixtures of phosphatidylcholines (PCs) and phosphatidylserines (PSs). The results indicate a mixture of electrostatic binding to anionic PS-rich domains as well as some nonspecific binding to the PC phase. Interestingly, both protein binding and scanning with synapsin-coated AFM tips can be used to visualize charged lipid domains that cannot be detected by topography alone.
Steacie Institute for Molecular Sciences, National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6, Canada.
Jill
J
Murray
Louis
L
Cuccia
Anatoli
A
Ianoul
James J
JJ
Cheetham
Linda J
LJ
Johnston
D000838:Anions / Q000737:chemistry; D007091:Image Processing, Computer-Assisted; D008051:Lipid Bilayers / Q000737:chemistry; D008563:Membrane Lipids / Q000737:chemistry*; D008567:Membranes, Artificial; D018625:Microscopy, Atomic Force / Q000379:methods; D020527:Microscopy, Scanning Probe; D010713:Phosphatidylcholines / Q000737:chemistry; D010718:Phosphatidylserines / Q000737:chemistry; D011485:Protein Binding; D012680:Sensitivity and Specificity; D013329:Structure-Activity Relationship; D016704:Synapsins / Q000737:chemistry*; D013572:Synaptic Vesicles / Q000737:chemistry
D000838:Anions; D008051:Lipid Bilayers; D008563:Membrane Lipids; D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D010718:Phosphatidylserines; D016704:Synapsins