FIG. 6.

Met-51 of M protein is essential for inhibition of nuclear export. (A) RNA export. Wild-type and mutant GST-M proteins were injected into the nucleus 1 h prior to the injection of RNA export substrates. Export of ³²P-labeled U1_Sm⁻ snRNA, AdML mRNA, and tRNA was monitored 1 and 3 h after RNA injection. RNA export was analyzed in the absence (a) or in the presence of the indicated amounts of GST-M (b), GST-M(51R) (c and d), GST-M(51L) (e), or GST-M(51A) (f) proteins. (B) GST-M protein stability and distributions. The nucleocytoplasmic distributions of GST-M proteins were monitored 2 and 5 h after nuclear injection of the indicated amounts of GST-M, GST-M(51R), GST-M(51L), or GST-M(51A) proteins.