A cDNA clone for a polyadenylated RNA-binding protein of Xenopus laevis oocytes hybridizes to four developmentally regulated mRNAs.

Xenopus laevis oocytes contain a unique group of proteins which decrease during oogenesis, bind poly(A) RNA, and possibly play a role in the regulation of translation. A monoclonal antibody generated against one of these proteins was used to screen an expression vector cDNA library. A cDNA clone was isolated and confirmed to code for the binding protein by in vitro translation of hybrid-selected RNA followed by immunoprecipitation. This cDNA, when used in RNA gel blots, hybridized to four transcripts of 2.0, 1.7 (two transcripts of similar size), and 1.2 kilobases. All of the transcripts decreased in amount during oogenesis and were not evident in somatic cells. In addition, the fraction of the transcripts associated with polysomes decreased during oogenesis. Digestion of the cDNA insert with PstI generated two fragments of 220 and 480 base pairs which, when used as probes in an RNA gel blot, hybridized to unique as well as common transcripts. Genomic Southern blots suggested the presence of a single gene, indicating that these transcripts arose by alternative processing.