VEB4 - EARLY ZYGOTIC MESSENGER-RNA EXPRESSED ASYMMETRICALLY ALONG THEANIMAL-VEGETAL AXIS OF THE SEA-URCHIN EMBRYO

We have analyzed a gene, designated VEB4, that is expressed transientl y in very early blastulae of the sea urchin, Strongylocentrotus purpur atus. Sequence analysis of the complete open reading frame shows that VEB4 encodes an unusual, highly charged protein with a pi of 9.55. We show here that VEB4 mRNA accumulate in-a spatial pattern that is indis tinguishable from that of two other recently described genes encoding metallo-endoproteases, SpAN, related to astacin and SpHE, the hatching enzyme (Reynolds et al. 1992). VEB4 and other members of this gene se t encode the earliest strictly zygotic gene products that have been id entified. The asymmetric accumulation of VEB4 mRNA in non-vegetal blas tomeres of the 16 cell embryo and their descendants reflects the anima l-vegetal maternal developmental axis.