tRNA nuclear export in XXXX : in situ hybridization analysis.

@entity17214 @entity66 @entity62844 @entity70743 @entity62843 @entity17215 @entity375
To understand the factors specifically affecting tRNA nuclear export, we adapted in situ hybridization procedures to locate endogenous levels of individual tRNA families in wild-type and mutant @entity375 cells. Our studies of tRNAs encoded by genes lacking introns show that nucleoporin @entity62844 affects both poly(A) RNA and tRNA export, whereas @entity62843 affects only poly(A) RNA export. @entity70743 is similar to exportin-t, which facilitates vertebrate tRNA export. A @entity70743 deletion mutation affects tRNA but not poly(A) RNA export. The data support the notion that @entity70743 and exportin-t are functional homologues. Because @entity70743 is nonessential, tRNA export in vertebrate and @entity375 cells likely involves factors in addition to exportin-t. Mutation of @entity17214 , which encodes RanGAP, causes nuclear accumulation of tRNAs and poly(A) RNA. Many @entity375 mutants, including those with the @entity17215 mutation, affect both pre-tRNA splicing and RNA export. Our studies of the location of intron-containing pre-tRNAs in the @entity17215 mutant rule out the possibility that this results from tRNA export occurring before splicing. Our results also argue against @entity66 causing defects in pre-tRNA splicing. Rather, the data support "feedback" of nucleus/cytosol exchange to the pre-tRNA splicing machinery.
