Veb4 - Early Zygotic Messenger-Rna Expressed Asymmetrically Along The Animal-Vegetal Axis Of The Sea-Urchin Embryo

We have analyzed a gene, designated VEB4, that is expressed transiently in very early blastulae of the sea urchin, Strongylocentrotus purpuratus. 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 indistinguishable 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 set encode the earliest strictly zygotic gene products that have been identified. The asymmetric accumulation of VEB4 mRNA in non-vegetal blastomeres of the 16 cell embryo and their descendants reflects the animal-vegetal maternal developmental axis.