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. 2001 Aug;12(8):2341–2351. doi: 10.1091/mbc.12.8.2341

Figure 4.

Figure 4

Expression of GFP-rab8WT and GFP-rab8Q67L downregulates the expression of endogenous rab8 in transgenic tadpoles. Equivalents of 1/8 of the retinas isolated from stage 51 tadpoles were subjected to SDS-PAGE and immunoblotted with anti-rab8 antibody (left panel) and anti-GFP antibody (right panel). In addition to a 23-kDa protein recognized by anti-rab8 antibody, transgenic retinas contain a 50-kDa protein that is also recognized by anti-GFP. The expression of GFP-rab8WT fusion protein under the control of the X. laevis rhodopsin promoter does not exceed that of endogenous rab8 as measured in the nontransgenic retina. However, the amount of the endogenous rab8 in these tadpoles is <50% of the nontransgenic animal. Therefore, the total content of rab8 (endogenous plus the fusion protein) is ∼1.5- to 2-fold higher than in the nontransgenic animals. In GFP-rab8Q67L tadpoles endogenous rab8 is also reduced to similar levels (<50% of control) as in GFP-rab8WT animals, and the fusion protein is in a threefold excess over the endogenous rab8. Because of the progressive retinal degeneration in GFP-rab8Q67L animals, the contribution of rod photoreceptors is lower than that in the retinas expressing GFP-rab8WT protein.