Figure 3.

(A) The Ndr2 protein encoded by the cyc^tf219 allele lacks a functional signal sequence, as judged by the failure to be glycosylated. Proteins from coupled transcription–translation reactions with expression plasmids that initiate at the wild-type met (WT) or the second met at position 38 (corresponding to cyc^tf219, denoted M) were analyzed under denaturing and reducing conditions. Aliquots were treated with or without dog pancreatic microsomes (Mic.) and±endoglycosidase H. The arrow indicates the glycosylated form of the polypeptide. (B) Northern blot analysis of the in vivo activity of wild-type (WT) and mutant (M) RNA in the Xenopus animal cap assay, using nrp-1 as a probe for neural induction (28). U, uninjected; pg, amount of RNA injected per embryo; 18S rRNA was used as a loading control; 7×, sevenfold longer exposure of the two lanes at the right to illustrate the inactivity of the mutant RNA.