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XB-ART-11591
Development February 1, 2000; 127 (4): 821-30.

BMP-binding modules in chordin: a model for signalling regulation in the extracellular space.

Larraín J , Bachiller D , Lu B , Agius E , Piccolo S , De Robertis EM .


Abstract
A number of genetic and molecular studies have implicated Chordin in the regulation of dorsoventral patterning during gastrulation. Chordin, a BMP antagonist of 120 kDa, contains four small (about 70 amino acids each) cysteine-rich domains (CRs) of unknown function. In this study, we show that the Chordin CRs define a novel protein module for the binding and regulation of BMPs. The biological activity of Chordin resides in the CRs, especially in CR1 and CR3, which have dorsalizing activity in Xenopus embryo assays and bind BMP4 with dissociation constants in the nanomolar range. The activity of individual CRs, however, is 5- to 10-fold lower than that of full-length Chordin. These results shed light on the molecular mechanism by which Chordin/BMP complexes are regulated by the metalloprotease Xolloid, which cleaves in the vicinity of CR1 and CR3 and would release CR/BMP complexes with lower anti-BMP activity than intact Chordin. CR domains are found in other extracellular proteins such as procollagens. Full-length Xenopus procollagen IIA mRNA has dorsalizing activity in embryo microinjection assays and the CR domain is required for this activity. Similarly, a C. elegans cDNA containing five CR domains induces secondary axes in injected Xenopus embryos. These results suggest that CR modules may function in a number of extracellular proteins to regulate growth factor signalling.

PubMed ID: 10648240
PMC ID: PMC2280033
Article link: Development
Grant support: [+]
Genes referenced: actl6a actn1 bmp2 bmp4 chrd.1 egf gcg myc pclo tbx2 tdgf1.1 tdgf1.2 tdgf1.3 tgfb1 thbs1 tll2
Antibodies: Somite Ab1


Article Images: [+] show captions
References [+] :
Ashe, Local inhibition and long-range enhancement of Dpp signal transduction by Sog. 1999, Pubmed, Xenbase


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