INDUCTION OF AXIAL MESODERM BY ZDVR-1, THE ZEBRAFISH ORTHOLOGUE OF XENOPUS VG1

The zebrafish DVR-1 (zDVR-1) gene, like Xenopus Vg1, is present matern ally as an unprocessed precursor protein which is distributed ubiquito usly along the future dorsoventral axis. Also, like Vg1, overexpressio n of zDVR-1 in zebrafish directs synthesis of more precursor, but no p rocessed protein. However, the native zDVR-1 precursor is processed to mature protein when expressed in Xenopus. Like processed Vg1, mature zDVR-1 is a potent inducer of axial mesoderm. The parallels in express ion pattern, apparent regulation of protein processing, and mesoderm-i nducing activity support the hypothesis that localized protein process ing controls production of a dorsal mesoderm inducer in these two spec ies. Furthermore, using mutant mRNAs, we show that cleavage site seque nces of the precursor protein are important in regulating protein proc essing. (C) 1996 Academic Press, Inc.