Multiple genes for Xenopus activin receptor expressed during early embryogenesis
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S Nishimatsu1, S Oda, K Murakami
1Institute of Applied Biochemistry, University of Tsukuba, Ibaraki, Japan.
Abstract:
Four distinct cDNAs for activin receptor designated as XSTK2, 3, 8 and 9 have been cloned from a Xenopus laevis cDNA library. The protein structures deduced from the cDNAs have shown that they all have a putative extracellular ligand-binding domain, a single transmembrane domain and cytoplasmic Ser/Thr kinase domain, except that XSTK2 is extremely similar to the XSTK3 gene but lacks a carboxyl-terminal part of the kinase motif. Northern blot analysis showed that all transcripts are maternally inherited. The levels of transcript for XSTK2, 3 and 8 appeared to fluctuate during early development while those for XSTK9 maintain constant.
Insights
Researchers identified four activin receptor genes in Xenopus laevis. These genes are maternally inherited, with distinct expression patterns during early development, suggesting roles in embryonic development.
Area of Science:
- Developmental Biology
- Molecular Biology
- Genetics
Background:
- Activin receptors are crucial for signal transduction pathways regulating cell differentiation and development.
- Understanding the diversity and expression of these receptors is key to deciphering developmental processes.
Purpose of the Study:
- To clone and characterize novel activin receptor genes from Xenopus laevis.
- To investigate the expression patterns of these newly identified genes during early Xenopus development.
Main Methods:
- Cloning of four distinct cDNAs (XSTK2, XSTK3, XSTK8, XSTK9) encoding activin receptors from a Xenopus laevis cDNA library.
- Deduction of protein structures from cDNA sequences.
- Northern blot analysis to examine transcript expression levels during early development.
Main Results:
- Four distinct activin receptor cDNAs were identified, sharing common structural features: an extracellular ligand-binding domain, a transmembrane domain, and a cytoplasmic Ser/Thr kinase domain.
- XSTK2 shares high similarity with XSTK3 but lacks a portion of the kinase motif.
- All identified transcripts are maternally inherited.
- Transcript levels for XSTK2, XSTK3, and XSTK8 fluctuate during early development, whereas XSTK9 transcript levels remain constant.
Conclusions:
- The identification of four distinct activin receptor genes in Xenopus laevis expands our understanding of the receptor family in this model organism.
- Maternal inheritance of transcripts suggests their importance from the earliest stages of development.
- Differential expression patterns indicate specialized roles for each receptor subtype in regulating Xenopus embryonic development.