Cloning by differential screening of a Xenopus cDNA coding for a protein highly homologous to cdc2.
Proc Natl Acad Sci U S A
; 88(3): 1039-43, 1991 Feb 01.
Article
em En
| MEDLINE
| ID: mdl-1704128
ABSTRACT
Fertilization of Xenopus laevis eggs triggers a period of rapid cell division comprising 12 nearly synchronous mitoses. Protein synthesis is required for these divisions, and new proteins appear after fertilization. Others proteins however, which are synthesized in the unfertilized egg, are no longer made in the early embryo. To identify such proteins, a differential screen of an egg cDNA library gave nine clones corresponding to mRNAs that are deadenylylated soon after fertilization. The sequence of one of these clones (Eg1) revealed a high homology to p34cdc2, the kinase subunit of maturation-promoting factor. Only 12 amino acids in the deduced amino acid sequence were unique to Eg1 when its sequence was compared to all other known examples of cdc2. Despite this strong similarity, however, Eg1 was unable to complement a yeast cdc2- mutant in Schizosaccharomyces pombe or a cdc28 mutant of Saccharomyces cerevisiae. Four Eg1 transcripts, two major and two minor, were found in Xenopus oocytes and early embryos. These RNAs appeared very early (stage I) in oogenesis and their level remained constant until the midblastula transition, at which time they declined. Eg1 RNA is found in the poly(A)+ fraction of oocytes only between the time of meiotic maturation and fertilization--that is to say, in the unfertilized egg. At fertilization the RNA loses its poly(A) tail and at the same time leaves the polyribosomes.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Fator Promotor de Maturação
/
Proteína Quinase CDC2
Tipo de estudo:
Diagnostic_studies
/
Prognostic_studies
/
Screening_studies
Limite:
Animals
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
1991
Tipo de documento:
Article
País de afiliação:
França