SCREENING OF PROTEIN-TYROSINE KINASES ACTIVATED DURING NEURAL INDUCTION IN XENOPUS

We have screened Xenopus animal cap ectodermal cells during neural ind uction for protein kinases (PK) and protein tyrosine kinases (PTKs) af ter their renaturation in gels containing the polydispersed substrate poly(Glu, Tyr). Following guanidine hydrochloride denaturation, renatu ration, and phosphorylation with [gamma-P-32]ATP, kinase activity was detected by autoradiography. Incubation of gels in hot alkali after gl utaraldehyde crosslinking completely eliminated the activity of non-PT K enzymes. This method is very sensitive and can be applied to develop ment biology for the detection of PTMs in very small samples such as e ctoderm explants dissected from animal caps in amphibian embryos. A la rge number of PTKs were visualized in uninduced and induced ectodermal cells. This procedure should be useful for investigating the role of PTKs in intracellular signaling during neural induction. (C) 1996 Acad emic Press, Inc.