We have previously cloned a type I serine/threonine kinase receptor from Xenopus, namely XTrR-I. We show here that XTrR-I is able to bind and mediate the activity of TGFβI, but is unable to mediate response to activin or BMP- 4. We have made a truncated receptor construct that can act as a dominant negative mutant receptor, and this can block the activity of TGFβ2 but not that of activin. Overexpression of either the full-length or truncated receptor has a drastic effect on mesoderm differentiation. The truncated receptor inhibits expression of notochord and muscle in mesodermalised animal caps, while the full-length receptor greatly increases the amount of notochord. In addition, the truncated receptor blocks the axis duplicating activity of both siamois and Xwnt8. We conclude that XTrR-I is involved in mediating a dorsalising activity important for mesoderm differentiation.
Mahony, D., Weis, F. M. B., Massagué, J., & Gurdon, J. B. (1998). XTrR-I is a TGFβ receptor and overexpression of a truncated form of the receptor inhibits axis formation and dorsalising activity. Mechanisms of Development, 75(1–2), 95–105. https://doi.org/10.1016/S0925-4773(98)00092-6