LOCALIZED MATERNAL PROTEINS IN XENOPUS REVEALED BY SUBTRACTIVE IMMUNIZATION

It has long been appreciated that the localization of cytoplasmic dete rminants in the egg can provide the foundation for patterning in the e mbryo. Differences in cell fate among the early blastomeres are thus a consequence of asymmetric distributions of informational molecules pr ior to fertilization. The frog egg has a single axis of asymmetry pres ent prior to fertilization, the animal/vegetal axis, and the localizat ion of developmental information appears to be polarized along this ax is. Such developmental information can be localized as either RNA or p rotein; localized RNAs are well documented in the Xenopus oocyte, and some are thought to play roles in axial patterning. While it is appare nt that not all of the localized maternal components are RNAs, much le ss is known about maternal proteins that might be localized in the In the present study, we have taken a novel approach to identify localize d maternal proteins within the Xenopus egg. Using a subtractive immuni zation strategy, we have generated monoclonal antibodies which recogni ze antigens that are restricted to the vegetal cortex of fertilized eg gs. Analysis of biogenesis during oogenesis reveals two distinct patte rns of localization to the cortex. At least three of these localized a ntigens are proteins, and these localized proteins could represent mat ernal determinants with roles in patterning. (C) 1997 Academic Press.