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. Author manuscript; available in PMC: 2010 Sep 29.
Published in final edited form as: Neuroscience. 2009 May 29;163(1):222–232. doi: 10.1016/j.neuroscience.2009.05.057

Figure 4. Rapsyn interacts with the β loop 407–469 region.

Figure 4

(A) CD4-β333–406 and CD4-β407–469 chimeras were expressed in COS cells alone or together with rapsyn. Rapsyn induced robust clustering of CD4-β407–469, but not CD4-β333–406. (B) Rapsyn-induced anchoring of CD4-β333–406 and -β407–469 was assayed by extracting transfected COS cells in 1% Triton-containing buffer and immunoblotting the soluble and pellet fractions with anti-CD4 antibody. With rapsyn co-expression, significant amounts of CD4-β loop and CD4-β407–469 were retained in the insoluble, cytoskeletal fraction, whereas CD4 and CD-β333–406 were recovered entirely in the soluble fraction. The pellet fraction was immunoblotted for rapsyn to show equivalent protein levels. (C) Quantification of the percentage of each protein retained in the insoluble fraction. Rapsyn anchored ~70% of CD4-β loop and ~40% of CD4-β407–469 (*p<0.05 by Student’s t-test; n=3). In contrast, the extractability of CD4 and CD4-β333–406 were not significantly affected by rapsyn.