Identification and expression of ventrally associated leucine-zipper (VAL) in Xenopus embryo.

In the present study, we have isolated a novel gene that is specifically expressed in the ventral region of Xenopus neurula and tailbud embryos. This gene, referred to as ventrally associated leucine-zipper (val), encodes for a novel class of protein consisting of a leucin-zipper motif, a glutamic acid-rich sequence and 5 repeats of proline-rich sequence. Expression of val started at the mid-gastrula stage, peaked at the early tailbud stage, and disappeared by the end of tailbud stage, and the endogenous expression of val was strictly dependent on BMP signaling. Myc-tagged val protein injected at early stage was accumulated in the nucleus at the gastrula stage and later, suggesting involvement of val in the process of ventral tissue formation during the neurula and tailbud stages.