Molecular characterization of a zebrafish TCF ETS-domain transcription factor

The ternary complex factor (TCF) subfamily of ETS-transcription factors rep resent key nuclear targets of the MAP kinase pathways. Members of this subf amily are classified by the presence of several conserved domains for DNA b inding, interaction with SRF, interaction with MAP kinases and transcriptio nal activation. In this study we have isolated a further member of this sub family (TCF-1) from zebrafish, The protein product of zebrafish TCF-1 (zTCF -1), shares sequence similarity with the mammalian TCFs in all four conserv ed domains, with highest overall similarity to SAP-1. Zebrafish TCF-1 is ex pressed throughout zebrafish embryonic development and exhibits typical TCF DNA binding characteristics, with the B-box being required for interaction with SRF, Of the mammalian TCFs, its DNA binding specificity resembles Elk -1. zTCF-1 is a target for both the growth factor/mitogen-activated and str ess-activated MAP kinase cascades in vitro and in vivo. However, differenti al targeting occurs, with the profile of its activation closely resembling that of mammalian SAP-1, Together, our results demonstrate that the TCFs ha ve been functionally conserved during vertebrate development.