β-TrCP interacts with and ubiquitinates PAPC and is required for normal <i>Xenopus</i> embryogenesis.

<p>(<b>A</b>) β-TrCP tagged with RFP co-localized with PAPC-GFP in animal cap cells, both on the plasma membrane and cytoplasmic punta (arrowheads). (<b>B</b>) Expression of TrCPΔF, a dominant-negative form of TrCP that lacks the F-box essential for E3 ligase complex formation, induced PAPC cytoplasmic aggregates in animal cap cells. Note the cells that appear rounder than those in (A). (<b>C</b>) GFP-tagged PAPCΔC was co-expressed with TrCPΔF in <i>Xenopus</i> DMZ cells. (<b>D</b>) TrCPΔF expression inhibited animal cap elongation when treated with activin. TrCPΔF also gave rise to gastrulation phenotypes such as defective blastopore closure and a shortened body axis.