The role of XTRAP-gamma in Xenopus pronephros development.

We isolated and characterized the Xenopus translocon-associated protein XTRAP-gamma, one of four subunits of the translocon-associated protein complex. TRAP has been proposed to aid the translocation of nascent polypeptides into the lumen of the endoplasmic reticulum, but this has not been demonstrated until now. XTRAP-gamma was specifically expressed in the pronephros tubules of Xenopus laevis from stage 25 during kidney development. Antisense morpholino oligonucleotide-mediated knockdown of XTRAP-gamma suppressed tubulogenesis and decreased expression of the pronephros marker genes Pax-2 and Wnt-4. XTRAP-gamma morpholinos also inhibited differentiation of the pronephros in activin/retinoic acid-treated animal caps. We conclude that XTRAP-gamma plays an important role in the process of pronephros differentiation.