Human and murine Evc proteins contain functional P‐loops and possess intrinsic GTPase activity

Evc is one of the novel proteins that have been implicated in the pathogenesis of Ellis van Creveld (EvC) syndrome and Weyers acrofacial dysostosis (WAD). EvC syndrome is a rare multi‐symptom human genetic disorder clinically characterized by mild short stature, postaxial polydactyly, dysplastic nail and teeth. Mutations in EVC and EVC2 genes that cause these syndromes introduce premature termination codons and frameshifts, resulting in production of defective Evc and Evc2 proteins respectively. Genetic and biochemical experiments have identified Evc and Evc2 as novel proteins that are essential for positive regulation of both Indian and sonic hedgehog (Hh) signaling pathways during bone and heart development, and pathogenesis of EvC syndrome. Two separate research reports demonstrated that Evc‐Evc2 complex interacts with smoothened (smo) at the base of the cilia to transduce Hh‐induced signal to downstream proteins. We present spectroscopic and immunochemical evidence to show that the putative P‐loop motif in Evc is functional and that it confers GTPase activity on the protein. Our findings have serious mechanistic implications on the transduction and regulation of Hh‐induced signals.