Fig. 8. CM-Der inhibits secretion of multiple members of the TGFß superfamily. Oocytes were injected with synthetic mRNA encoding epitope tagged proAct-Xnr2 (HA tagged), proAct-Derrière (Flag tagged) or BMP4 either alone or in combination with CM-Der. Injected oocytes were cultured in the presence of [35S]methionine and the supernatants and lysates analyzed by immunoprecipitation. Supernatants from oocytes expressing proAct-Xnr2, proAct-Derrière or BMP4 alone contain bands corresponding to the predicted sizes of the mature ligands, while the lysates also contain higher molecular weight unprocessed precursor proteins (lanes 1-3). CM-Der (tagged with the Glu-Glu epitope) is seen only in oocyte lysates and in its presence no mature Xnr2, Derrière or BMP4 ligands are detected in the supernatants (lanes 4-7). Unprocessed precursor proteins are still detected in oocyte lysates. Asterisks indicate unprocessed BMP4; arrowheads indicate mature Xnr2 and Derrière ligands.