title: Nucleocytoplasmic distribution of snRNPs and stockpiled snRNA-binding proteins during oogenesis and early development in Xenopus laevis.
abstract: The distribution of small nuclear ribonucleoprotein particles containing U snRNAs (U snRNPs) during oogenesis and early development in Xenopus was analyzed with a lupus antibody (anti-Sm) that reacts with snRNA-binding proteins. Fully grown oocytes and embryos prior to gastrulation were found to be relatively depleted of U snRNPs in their nuclei and to contain an excess of snRNA-binding proteins stored in the cytoplasm. During late blastula-early gastrula, or after microinjection of U snRNAs into the cytoplasm of a mature oocyte, the proteins migrate into the nucleus. Dot hybridization analysis showed that small previtellogenic oocytes already contain a maximal amount of U1 (and U2) snRNAs, which then decreases to about 20% of that value in fully mature oocytes, even though the cell's volume has increased enormously. Thus fully grown oocytes and eggs accumulate snRNA-binding proteins for use during early development, but this is not coupled with the accumulation of U snRNA.
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000378:metabolism*; D005260:Female; D005775:Gastrula / Q000378:metabolism; D008845:Microinjections; D009698:Nucleoproteins / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism*; D009866:Oogenesis; D010063:Ovum / Q000378:metabolism*; D012313:RNA / Q000378:metabolism; D012342:RNA, Small Nuclear; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins / Q000378:metabolism*; D017411:Ribonucleoproteins, Small Nuclear; D014982:Xenopus laevis
chemical_list: D002352:Carrier Proteins; D009698:Nucleoproteins; D012342:RNA, Small Nuclear; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear; D012313:RNA