Binding of NAP-22, a calmodulin-binding neuronal protein, to raft-like domains in model membranes.
The cholesterol-binding protein NAP-22 is a major component of the detergent-insoluble low-density fraction of rat brain. In this study, we found, using fluorescence microscopy, that native NAP-22, but not a demyristoylated form, binds to cholesterol-rich raft-like domains in planar-supported monolayers and remains bound after nonionic detergent extraction. NAP-22 also protects the cholesterol-rich domains during extraction by methyl-beta-cyclodextrin. The lateral mobility of this protein is much lower than that of other raft components in model membranes, suggesting that both cholesterol binding and inter-NAP-22 interactions markedly reduce its lateral diffusion. This study suggests that NAP-22 binding may be employed to image cholesterol-rich regions, such as caveolae/rafts, on the plasma membrane of cells, and preliminary efforts in that direction are presented.
Khan
Tapan K
TK
Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
Yang
Bing
B
Thompson
Nancy L
NL
Maekawa
Shohei
S
Epand
Richard M
RM
Jacobson
Ken
K
D016475:3T3 Cells; D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000378:metabolism; D002148:Calmodulin-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002784:Cholesterol; D003001:Cloning, Molecular; D003598:Cytoskeletal Proteins; D004926:Escherichia coli / Q000235:genetics; D005677:G(M1) Ganglioside / Q000378:metabolism; D008081:Liposomes / Q000378:metabolism; D021962:Membrane Microdomains / Q000378:metabolism*; D008567:Membranes, Artificial; D051379:Mice; D008954:Models, Biological; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
C489363:Basp1 protein, mouse; D002148:Calmodulin-Binding Proteins; D003598:Cytoskeletal Proteins; D008081:Liposomes; D008567:Membranes, Artificial; D009419:Nerve Tissue Proteins; D011994:Recombinant Proteins; C066853:Basp1 protein, rat; D005677:G(M1) Ganglioside; D002784:Cholesterol