@article {528231,
	title = {The {\textquoteleft}RGD finger{\textquoteright} of Del-1 is a unique structural feature critical for integrin binding},
	journal = {FASEB J.},
	volume = {26},
	year = {2012},
	pages = {3412-20},
	abstract = {Developmental endothelial cell locus-1 (Del-1) glycoprotein is secreted by endothelial cells and a subset of macrophages.\&nbsp;Del-1plays a regulatory role in vascular remodeling and functions in innate immunity through interaction with\&nbsp;integrin\&nbsp;α(V)β(3).\&nbsp;Del-1contains 3 epidermal growth factor (EGF)-like repeats and 2 discoidin-like domains. An Arg-Gly-Asp (RGD) motif in the second EGF domain (EGF2) mediates adhesion by endothelial cells and phagocytes. We report the crystal structure of its 3 EGF domains. TheRGD\&nbsp;motif of EGF2 forms a type II{\textquoteright} β turn at the tip of a long protruding loop, dubbed the\&nbsp;RGD\&nbsp;finger. Whereas EGF2 and EGF3 constitute a rigid rod via an interdomain calcium ion\&nbsp;binding\&nbsp;site, the long linker between EGF1 and EGF2 lends considerable flexibility to EGF1. Two\&nbsp;unique\&nbsp;O-linked glycans and 1 N-linked glycan locate to the opposite side of EGF2 from the\&nbsp;RGD\&nbsp;motif. These\&nbsp;structural\&nbsp;features favor\&nbsp;integrin\&nbsp;binding\&nbsp;of the\&nbsp;RGD\&nbsp;finger. Mutagenesis data confirm the importance of having the\&nbsp;RGD\&nbsp;motif at the tip of the\&nbsp;RGD\&nbsp;finger. A database search for EGF domain sequences shows that this\&nbsp;RGD\&nbsp;finger\&nbsp;is likely an evolutionary insertion and\&nbsp;unique\&nbsp;to the EGF domain of\&nbsp;Del-1\&nbsp;and its homologue milk fat globule-EGF 8.},
	author = {Sch{\"u}rpf, T. and Chen, Q. and Liu, J-H. and Wang, R. and Springer, T. and J.-H. Wang}
}
