Proline365 is a critical residue for the activity of XMI-ER1 in Xenopus embryonic development.

Xmi-er1 is an immediate-early gene encoding a transcriptional regulator whose expression is activated by fibroblast growth factor (FGF) during mesoderm induction in Xenopus. In this study, we examined the role of xmi-er1 in embryonic development and mesoderm induction and investigated the importance of various functional domains in the protein sequence. Overexpression of xmi-er1 in embryos resulted in truncations of the anteroposterior axis, with most of the abnormal embryos exhibiting deficiencies in both anterior and posterior structures.