A Xenopus homologue of the human beta-amyloid precursor protein: developmental regulation of its gene expression.

Complimentary DNA clones have been isolated from Xenopus larva to delineate a protein highly homologous to the human beta-amyloid precursor protein (APP). Developmental change of Xenopus APP gene expression has been analyzed with molecular probes. From early oogenesis, there is a high accumulation of maternal APP. After fertilization, the mRNA is degraded, reaching a minimum level around the gastrula stage. Then zygotic transcription appears to be initiated, and this continues during the subsequent embryonic and larval stages. Splicing patterns differ between the maternal and zygotic transcripts. The ratio of mRNA including the protease inhibitor domain (PID) sequence is extremely low for the transcript of maternal origin as compared to that for the transcript of zygotic origin. These results suggest some roles for the APP molecule in Xenopus early development.