Taxonomic distribution of proteins containing CHRD domains

The tree below includes only several representative species and genera. The complete taxonomic breakdown of all proteins containing CHRD domains can be accessed here. Click the counts or percentage values to display the corresponding proteins.

CHRD, a novel domain in the BMP inhibitor chordin, is also found in microbial proteins.

Hyvonen M
Trends Biochem Sci. 2003; 28: 470-3

CHRD (after SWISSPROT abbreviation for chordin) is a novel domain identified in chordin, an inhibitor of bone morphogenetic proteins. Database searches have revealed several microbial homologues to this domain. It is anticipated to have an immunoglobulin-like beta-barrel structure based on limited similarity to superoxide dismutases but, as yet, no clear functional prediction can be made.

Dorsoventral patterning in Xenopus: inhibition of ventral signals by direct binding of chordin to BMP-4.

Piccolo S, Sasai Y, Lu B, De Robertis EM
Cell. 1996; 86: 589-98

Chordin (Chd) is an abundant protein secreted by Spemann organizer tissue during gastrulation. Chd antagonizes signaling by mature bone morphogenetic proteins (BMPs) by blocking binding to their receptors. Recombinant Xenopus Chd binds to BMP-4 with high affinity (KD, 3 x 10(-10) M), binding specifically to BMPs but not to activin or TGF-beta1. Chd protein is able to dorsalize mesoderm and to neuralize ectoderm in Xenopus gastrula explants at 1 nM. We propose that the noncell-autonomous effects of Spemann's organizer on dorsoventral patterning are executed in part by diffusible signals that directly bind to and neutralize ventral BMPs during gastrulation.

A conserved system for dorsal-ventral patterning in insects and vertebrates involving sog and chordin.

Holley SA, Jackson PD, Sasai Y, Lu B, DeRobertis EM, Hoffmann FM, Ferguson EL
Nature. 1995; 376: 249-53

Dorsal-ventral patterning within the ectoderm of the Drosophila embryo requires seven zygotic genes, including short gastrulation (sog). Here we demonstrate that sog, which is expressed in the ventrolateral region of the embryo that gives rise to the nerve cord, is functionally homologous to the chordin gene of Xenopus, which is expressed in the dorsal blastopore lip of the embryo and in dorsal mesoderm, in particular the notochord. We show by injections of messenger RNA that both sog and chordin can promote ventral development in Drosophila, and that sog, like chordin, can promote dorsal development in Xenopus. In Drosophila, sog antagonizes the dorsalizing effects of decapentaplegic (dpp), a member of the transforming growth factor-beta family. One of the dpp homologues in vertebrates, bmp-4, is expressed ventrally in Xenopus and promotes ventral development. We show that dpp can promote ventral fates in Xenopus, and that injection of sog mRNA counteracts the ventralizing effects of dpp. These results suggest the molecular conservation of dorsoventral patterning mechanisms during evolution.

Xenopus chordin: a novel dorsalizing factor activated by organizer-specific homeobox genes.

Sasai Y, Lu B, Steinbeisser H, Geissert D, Gont LK, De Robertis EM
Cell. 1994; 79: 779-90

A Xenopus gene whose expression can be activated by the organizer-specific homeobox genes goosecoid and Xnot2 was isolated by differential screening. The chordin gene encodes a novel protein of 941 amino acids that has a signal sequence and four Cys-rich domains. The expression of chordin starts in Spemann's organizer subsequent to that of goosecoid, and its induction by activin requires de novo protein synthesis. Microinjection of chordin mRNA induces twinned axes and can completely rescue axial development in ventralized embryos. This molecule is a potent dorsalizing factor that is expressed at the right time and in the right place to regulate cell-cell interactions in the organizing centers of head, trunk, and tail development.