Minor-class splicing occurs in the nucleus of the Xenopus oocyte.
A small fraction of premessenger RNA introns in certain eukaryotes is excised by the minor spliceosome, which contains low-abundance small nuclear ribonucleoproteins (snRNPs). Recently, it was suggested that minor-class snRNPs are localized to and function in the cytoplasm of vertebrate cells. To test whether U12-type splicing occurs in the cytoplasm of Xenopus oocytes, we performed microinjections of the well-characterized P120 minor-class splicing substrate into the nucleus or into the cytoplasm. Our results demonstrate that accurate splicing of this U12-dependent intron occurs exclusively in the nuclear compartment of the oocyte, where U12 and U6atac snRNPs are primarily localized. We further demonstrate that splicing of both a major-class and a minor-class intron is inhibited after nuclear envelope breakdown during meiosis.
Kyle
K
Friend
Nikolay G
NG
Kolev
Mei-Di
MD
Shu
Joan A
JA
Steitz
D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*; D012326:RNA Splicing; D012342:RNA, Small Nuclear / Q000378:metabolism; D017411:Ribonucleoproteins, Small Nuclear / Q000378:metabolism; D017381:Spliceosomes; D014982:Xenopus laevis / Q000378:metabolism*
D012342:RNA, Small Nuclear; D017411:Ribonucleoproteins, Small Nuclear; C096986:U12 small nuclear RNA